1
|
Rossi D, Dong Y, Paradkar R, Chen X, Wu Y, Mohler C, Kuo TC, Chen Z. Quantifying Chemical Reactions and Interfacial Properties at Buried Polymer/Polymer Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:12689-12696. [PMID: 38842226 DOI: 10.1021/acs.langmuir.4c01214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
Maleic anhydride (MAH)-modified polymers are used as tie layers for binding dissimilar polymers in multilayer polymer films. The MAH chemistry which promotes adhesion is well characterized in the bulk; however, only recently has the interfacial chemistry been studied. Sum frequency generation vibrational spectroscopy (SFG) is an interfacial spectroscopy technique which provides detailed information on interfacial chemical reactions, species, and molecular orientations and has been essential for characterizing the MAH chemistry in both nylon and ethyl vinyl alcohol copolymer (EVOH) model systems and coextruded multilayer films. Here, we further characterize the interfacial chemistry between MAH-modified polyethylene tie layers and both EVOH and nylon by investigating the model systems over a range of MAH concentrations. We can detect the interfacial chemical reaction products between MAH and the barrier layer at MAH concentrations of ≥0.022 wt % for nylon and ≥0.077 wt % for EVOH. Additionally, from the concentration-dependent reaction reactant/product SFG peak positions and the product imide or ester/acid C═O group tilt angles extracted from the polarization-dependent SFG spectra, we quantitatively observe concentration-dependent changes to both the interfacial chemistry and interfacial structure. The interfacial chemistry and molecular orientation as a function of MAH concentration are well correlated with the adhesion strength, providing important quantitative information for the future design of MAH-modified tie layers for a variety of important applications.
Collapse
Affiliation(s)
- Daniel Rossi
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Yifan Dong
- Packaging and Specialty Plastics, The Dow Chemical Company, Lake Jackson, Texas 77566, United States
| | - Rajesh Paradkar
- Packaging and Specialty Plastics, The Dow Chemical Company, Lake Jackson, Texas 77566, United States
| | - Xiaoyun Chen
- Core R&D, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Yuchen Wu
- Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Carol Mohler
- Core R&D, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Tzu-Chi Kuo
- Core R&D, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
2
|
Zheng X, Ni Z, Pei Q, Wang M, Tan J, Bai S, Shi F, Ye S. Probing the Molecular Structure and Dynamics of Membrane-Bound Proteins during Misfolding Processes by Sum-Frequency Generation Vibrational Spectroscopy. Chempluschem 2024; 89:e202300684. [PMID: 38380553 DOI: 10.1002/cplu.202300684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/17/2024] [Accepted: 02/20/2024] [Indexed: 02/22/2024]
Abstract
Protein misfolding and amyloid formation are implicated in the protein dysfunction, but the underlying mechanism remains to be clarified due to the lack of effective tools for detecting the transient intermediates. Sum frequency generation vibrational spectroscopy (SFG-VS) has emerged as a powerful tool for identifying the structure and dynamics of proteins at the interfaces. In this review, we summarize recent SFG-VS studies on the structure and dynamics of membrane-bound proteins during misfolding processes. This paper first introduces the methods for determining the secondary structure of interfacial proteins: combining chiral and achiral spectra of amide A and amide I bands and combining amide I, amide II, and amide III spectral features. To demonstrate the ability of SFG-VS in investigating the interfacial protein misfolding and amyloid formation, studies on the interactions between different peptides/proteins (islet amyloid polypeptide, amyloid β, prion protein, fused in sarcoma protein, hen egg-white lysozyme, fusing fusion peptide, class I hydrophobin SC3 and class II hydrophobin HFBI) and surfaces such as lipid membranes are discussed. These molecular-level studies revealed that SFG-VS can provide a unique understanding of the mechanism of interfacial protein misfolding and amyloid formation in real time, in situ and without any exogenous labeling.
Collapse
Affiliation(s)
- Xiaoxuan Zheng
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Zijian Ni
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Quanbing Pei
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Mengmeng Wang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Junjun Tan
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Shiyu Bai
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Fangwen Shi
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Shuji Ye
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| |
Collapse
|
3
|
Labrague G, Gomez F, Chen Z. Characterization of Buried Interfaces of Silicone Materials in Situ to Understand Their Fouling-Release, Antifouling, and Adhesion Properties. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:9345-9361. [PMID: 38669686 DOI: 10.1021/acs.langmuir.4c00615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
Poly(dimethylsiloxane) (PDMS) has numerous excellent properties and is extensively used as the main component of many silicone products in a variety of research fields and practical applications such as biomedical materials, aviation, construction, electronic devices, and automobiles. Interfacial structures of PDMS and other components in silicone systems are important for such research and applications. It is difficult to probe interfacial molecular structures of buried solid-liquid and solid-solid interfaces of silicone materials due to the lack of appropriate analytical tools. In this feature article, we presented our research on elucidating the molecular structures of PDMS as well as other additives in silicone samples at buried interfaces in situ at the molecular level using a nonlinear optical spectroscopic technique, sum frequency generation (SFG) vibrational spectroscopy. SFG was applied to study various PDMS surfaces in liquid environments to understand their fouling-release and antifouling activities. SFG has also been used to study buried solid-solid interfaces between silicone adhesives and polymers, elucidating the molecular adhesion mechanisms. Our SFG studies provide important knowledge on interfacial structure-function relationships of silicone materials, helping the design and development of silicone materials with improved properties through optimization of silicone interfacial structures.
Collapse
Affiliation(s)
- Gladwin Labrague
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Fernando Gomez
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
4
|
Mengel SD, Guo W, Wu G, Finlay JA, Allen P, Clare AS, Medhi R, Chen Z, Ober CK, Segalman RA. Diffusely Charged Polymeric Zwitterions as Loosely Hydrated Marine Antifouling Coatings. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:282-290. [PMID: 38131624 DOI: 10.1021/acs.langmuir.3c02492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Polymeric zwitterions exhibit exceptional fouling resistance through the formation of a strongly hydrated surface of immobilized water molecules. While being extensively tested for their performance in biomedical, membrane, and, to a lesser extent, marine environments, few studies have investigated how the molecular design of the zwitterion may enhance its performance. Furthermore, while theories of zwitterion antifouling mechanisms exist for molecular-scale foulant species (e.g., proteins and small molecules), it remains unclear how molecular-scale mechanisms influence the micro- and macroscopic interactions of relevance for marine applications. The present study addresses these gaps through the use of a modular zwitterion chemistry platform, which is characterized by a combination of surface-sensitive sum frequency generation (SFG) vibrational spectroscopy and marine assays. Zwitterions with increasingly delocalized cations demonstrate improved fouling resistance against the green alga Ulva linza. SFG spectra correlate well with the assay results, suggesting that the more diffuse charges exhibit greater surface hydration with more bound water molecules. Hence, the number of bound interfacial water molecules appears to be more influential in determining the marine antifouling activities of zwitterionic polymers than the binding strength of individual water molecules at the interface.
Collapse
Affiliation(s)
- Shawn D Mengel
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Wen Guo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48103, United States
| | - Guangyao Wu
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48103, United States
| | - John A Finlay
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Peter Allen
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Anthony S Clare
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Riddhiman Medhi
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14583, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48103, United States
| | - Christopher K Ober
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14583, United States
| | - Rachel A Segalman
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Materials, University of California, Santa Barbara, California 93106, United States
- Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, United States
| |
Collapse
|
5
|
Carpenter AP, Golbek TW. "Nonlinear" pursuit of understanding pollutant accumulation and chemistry at environmental and biological interfaces. Biointerphases 2023; 18:058501. [PMID: 37728303 DOI: 10.1116/6.0003059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 08/25/2023] [Indexed: 09/21/2023] Open
Abstract
Over the past few decades, the public recognition of the prevalence of certain classes of pollutants, such as perfluoroalkyl substances and nanoplastics, within the environment, has sparked growing concerns over their potential impact on environmental and human health. Within both environmental and biological systems, the adsorption and structural organization of pollutants at aqueous interfaces can greatly impact the chemical reactivity and transformation. Experimentally probing chemical behavior at interfaces can often pose a problem due to bulk solvated molecules convoluting molecular signatures from interfacial molecules. To solve this problem, there exist interface-specific nonlinear spectroscopy techniques that can directly probe both macroscopic planar interfaces and nanoplastic interfaces in aqueous environments. These techniques can provide essential information such as chemical adsorption, structure, and reactivity at interfaces. In this perspective, these techniques are presented with obvious advantages for studying the chemical properties of pollutants adsorbed to environmental and biological interfaces.
Collapse
Affiliation(s)
- Andrew P Carpenter
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331
| | | |
Collapse
|
6
|
Wu Y, Wang T, Gao J, Zhang L, Fay JDB, Hirth S, Hankett J, Chen Z. Molecular Behavior of 1K Polyurethane Adhesive at Buried Interfaces: Plasma Treatment, Annealing, and Adhesion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:3273-3285. [PMID: 36808974 DOI: 10.1021/acs.langmuir.2c03084] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
One-part (1K) polyurethane (PU) adhesive has excellent bulk strength and environmental resistance. It is therefore widely used in many fields, such as construction, transportation, and flexible lamination. However, when contacting non-polar polymer materials, the poor adhesion of 1K PU adhesive may not be able to support its outdoor applications. To solve this problem, plasma treatment of the non-polar polymer surface has been utilized to improve adhesion between the polymer and 1K PU adhesive. The detailed mechanisms of adhesion enhancement of the 1K PU adhesive caused by plasma treatment on polymer substrates have not been studied extensively because adhesion is a property of buried interfaces which are difficult to probe. In this study, sum frequency generation (SFG) vibrational spectroscopy was used to investigate the buried PU/polypropylene (PP) interfaces in situ nondestructively. Fourier-transform infrared spectroscopy, the X-ray diffraction technique, and adhesion tests were used as supplemental methods to SFG in the study. The 1K PU adhesive is a moisture-curing adhesive and usually needs several days to be fully cured. Here, time-dependent SFG experiments were conducted to monitor the molecular behaviors at the buried 1K PU adhesive/PP interfaces during the curing process. It was found that the PU adhesives underwent rearrangement during the curing process with functional groups gradually becoming ordered at the interface. Stronger adhesion between the plasma-treated PP substrate and the 1K PU adhesive was observed, which was achieved by the interfacial chemical reactions and a more rigid interface. Annealing the samples increased the reaction speed and enhanced the bulk PU strength with higher crystallinity. In this research, molecular mechanisms of adhesion enhancement of the 1K PU adhesive caused by the plasma treatment on PP and by annealing the PU/PP samples were elucidated.
Collapse
Affiliation(s)
- Yuchen Wu
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Tianle Wang
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jinpeng Gao
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Lu Zhang
- BASF Corporation, 1609 Biddle Avenue, Wyandotte, Michigan 48192, United States
| | - Jonathan D B Fay
- BASF Corporation, 1609 Biddle Avenue, Wyandotte, Michigan 48192, United States
| | - Sabine Hirth
- BASF SE, RAA/OS-B007, Carl-Bosch-Strasse 38, 67056 Ludwigshafen am Rhein, Germany
| | - Jeanne Hankett
- BASF Corporation, 1609 Biddle Avenue, Wyandotte, Michigan 48192, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
7
|
Carr AJ, Lee SE, Kumal RR, Bu W, Uysal A. Convenient Confinement: Interplay of Solution Conditions and Graphene Oxide Film Structure on Rare Earth Separations. ACS APPLIED MATERIALS & INTERFACES 2022; 14:57133-57143. [PMID: 36533427 DOI: 10.1021/acsami.2c16156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Graphene oxide (GO) membranes are excellent candidates for a range of separation applications, including rare earth segregation and radionuclide decontamination. Understanding nanoscale water and ion behavior near interfacial GO is critical for groundbreaking membrane advances, including improved selectivity and permeability. We experimentally examine the impact of solution conditions on water and lanthanide interactions with interfacial GO films and connect these results to GO membrane performance. The investigation of the confined films at the air-water interface with a combination of surface-specific spectroscopy and X-ray scattering techniques allows us to understand water and ion behaviors separately. Sum frequency generation spectroscopy reveals a dramatic change in interfacial water organization because of graphene oxide film deprotonation. Interfacial X-ray fluorescence measurements show a 17× increase in adsorbed lanthanide to the GO film from subphase pH 3 to pH 9. Liquid surface X-ray reflectivity data show an additional 2.7 e- per Å2 for GO films at pH 9 versus pH 3 as well. These results are connected to GO membrane performance, which show increased selectivity and decreased flux for membranes filtering pH 9 solutions. We posit insoluble lanthanide hydroxides form at higher pHs. Taken together, these results highlight the importance of interfacial experiments on model GO systems.
Collapse
Affiliation(s)
- Amanda J Carr
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois60439, United States
| | - Seung Eun Lee
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois60439, United States
| | - Raju R Kumal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois60439, United States
| | - Wei Bu
- NSF's ChemMatCARS, The University of Chicago, Chicago, Illinois60637, United States
| | - Ahmet Uysal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois60439, United States
| |
Collapse
|
8
|
Page EF, Blake MJ, Foley GA, Calhoun TR. Monitoring membranes: The exploration of biological bilayers with second harmonic generation. CHEMICAL PHYSICS REVIEWS 2022; 3:041307. [PMID: 36536669 PMCID: PMC9756348 DOI: 10.1063/5.0120888] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 11/03/2022] [Indexed: 12/23/2022]
Abstract
Nature's seemingly controlled chaos in heterogeneous two-dimensional cell membranes stands in stark contrast to the precise, often homogeneous, environment in an experimentalist's flask or carefully designed material system. Yet cell membranes can play a direct role, or serve as inspiration, in all fields of biology, chemistry, physics, and engineering. Our understanding of these ubiquitous structures continues to evolve despite over a century of study largely driven by the application of new technologies. Here, we review the insight afforded by second harmonic generation (SHG), a nonlinear optical technique. From potential measurements to adsorption and diffusion on both model and living systems, SHG complements existing techniques while presenting a large exploratory space for new discoveries.
Collapse
Affiliation(s)
- Eleanor F. Page
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Marea J. Blake
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Grant A. Foley
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Tessa R. Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| |
Collapse
|
9
|
Polymer-solvent interaction and conformational changes at a molecular level: Implication to solvent-assisted deformation and aggregation at the polymer surface. J Colloid Interface Sci 2022; 616:221-233. [DOI: 10.1016/j.jcis.2022.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 02/01/2022] [Accepted: 02/02/2022] [Indexed: 11/17/2022]
|
10
|
Andre JS, Grant J, Greyson E, Chen X, Tucker C, Drumright R, Mohler C, Chen Z. Molecular Interactions between Amino Silane Adhesion Promoter and Acrylic Polymer Adhesive at Buried Silica Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6180-6190. [PMID: 35512318 DOI: 10.1021/acs.langmuir.2c00602] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this study, the influence of an amino silane (3-(2-aminoethylamino)-propyldimethoxymethylsilane, AEAPS) on the interfacial structure and adhesion of butyl acrylate/methyl methacrylate copolymers (BAMMAs) to silica was investigated by sum frequency generation vibrational spectroscopy (SFG). Small amounts of methacrylic acid, MAA, were included in the BAMMA polymerizations to assess the impact of carboxylic acid functionality on the glass interface. SFG was used to probe the O-H and C═O groups of incorporated MAA, ester C═O groups of BAMMA, and CH groups from all species at the silica interfaces. The addition of AEAPS resulted in a significant change in the molecular structure of the polymer at the buried interface with silica due to specific interactions between the BAMMA polymers and silane. SFG results were consistent with the formation of ionic bonds between the primary and secondary amines of the AEAPS tail group and the MAA component of the polymer, as evidenced by the loss of the MAA O-H and C═O signals at the interface. It is extensively reported in the literature that methoxy head groups of an amino silane chemically bind to the silanols of glass, leaving the amine groups available to react with various chemical functionalities. Our results are consistent with this scenario and support an adhesion promotion mechanism of amino silane with various aspects: (1) the ionic bond formation between the tail amine group and acid functionality on BAMMA, (2) the chemical coupling between the silane head group and glass, (3) migration of more ester C═O groups to the interface with order, and (4) disordering or reduced levels of CH groups at the interface. These results are important for better understanding of the mechanisms and effect of amino silanes on the adhesion between acrylate polymers and glass substrates in a variety of applications.
Collapse
Affiliation(s)
- John S Andre
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Joseph Grant
- Dow Coating Materials, Collegeville, Pennsylvania 19426, United States
| | - Eric Greyson
- Dow Coating Materials, Collegeville, Pennsylvania 19426, United States
| | - Xiaoyun Chen
- The Dow Chemical Company, Core R&D, Midland, Michigan 48674, United States
| | - Christopher Tucker
- The Dow Chemical Company, Core R&D, Midland, Michigan 48674, United States
| | - Ray Drumright
- Dow Coating Materials, Midland, Michigan 48674, United States
| | - Carol Mohler
- The Dow Chemical Company, Core R&D, Midland, Michigan 48674, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
11
|
Affiliation(s)
- Guido Raos
- Department of Chemistry, Materials and Chemical Engineering “G. Natta”, Politecnico di Milano, Via L. Mancinelli 7, I-20131 Milano, Italy
| | - Bruno Zappone
- Consiglio Nazionale delle Ricerche - Istituto di Nanotecnologia (CNR-Nanotec), Via P. Bucci, 33/C, 87036 Rende (CS), Italy
| |
Collapse
|
12
|
Zhang S, Hsu L, Toolis A, Li B, Zhou J, Lin T, Chen Z. Investigation of the Atmospheric Moisture Effect on the Molecular Behavior of an Isocyanate-Based Primer Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12705-12713. [PMID: 34668715 DOI: 10.1021/acs.langmuir.1c02135] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A primer coating is engineered to facilitate compatibility between products like adhesives, sealants, and potting compounds and targeted substrates. Prolonged exposure of isocyanate-based primer surfaces to the environment is known to negatively affect the interfacial adhesion between itself and the products subsequently applied on top of it. However, the molecular behavior behind this observed phenomenon remained to be further investigated. In this study, sum frequency generation (SFG) vibrational spectroscopy, a nonlinear optical spectroscopic technique, was applied to study the surface of an isocyanate-based primer exposed to different environments at the molecular level. Atmospheric moisture was considered to be a potential factor in impairing the adhesion performance of the primer, and thus, time- and humidity-dependent experiments were executed to monitor the molecular behavior at the primer surface using SFG. In addition, 180° peel testing experiments were conducted to measure the adhesion properties of primers after being exposed to the corresponding conditions to correlate to SFG results and establish a chemical structure-macroscopic performance relationship. This study on the changes at the primer surface in different environments with varied humidity levels as a function of time aims to provide an in-depth understanding of the moisture effect on isocyanate-based primers. These learnings may also be helpful toward exploring a broader range of coatings and surface layers and improving customer product use guidelines.
Collapse
Affiliation(s)
| | - Lorraine Hsu
- Coatings and Innovation Center, PPG, 4325 Rosanna Drive, Allison Park, Pennsylvania 15101, United States
| | - Amy Toolis
- Coatings and Innovation Center, PPG, 4325 Rosanna Drive, Allison Park, Pennsylvania 15101, United States
| | | | | | | | | |
Collapse
|
13
|
Guo W, Lu T, Gandhi Z, Chen Z. Probing Orientations and Conformations of Peptides and Proteins at Buried Interfaces. J Phys Chem Lett 2021; 12:10144-10155. [PMID: 34637311 DOI: 10.1021/acs.jpclett.1c02956] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Molecular structures of peptides/proteins at interfaces determine their interfacial properties, which play important roles in many applications. It is difficult to probe interfacial peptide/protein structures because of the lack of appropriate tools. Sum frequency generation (SFG) vibrational spectroscopy has been developed into a powerful technique to elucidate molecular structures of peptides/proteins at buried solid/liquid and liquid/liquid interfaces. SFG has been successfully applied to study molecular interactions between model cell membranes and antimicrobial peptides/membrane proteins, surface-immobilized peptides/enzymes, and physically adsorbed peptides/proteins on polymers and 2D materials. A variety of other analytical techniques and computational simulations provide supporting information to SFG studies, leading to more complete understanding of structure-function relationships of interfacial peptides/proteins. With the advance of SFG techniques and data analysis methods, along with newly developed supplemental tools and simulation methodology, SFG research on interfacial peptides/proteins will further impact research in fields like chemistry, biology, biophysics, engineering, and beyond.
Collapse
Affiliation(s)
- Wen Guo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Tieyi Lu
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Zahra Gandhi
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
14
|
Lautenbach V, Hosseinpour S, Peukert W. Isoelectric Point of Proteins at Hydrophobic Interfaces. Front Chem 2021; 9:712978. [PMID: 34395381 PMCID: PMC8360839 DOI: 10.3389/fchem.2021.712978] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 07/19/2021] [Indexed: 12/02/2022] Open
Abstract
Structural and colloidal stability of proteins at different surfaces and interfaces is of great importance in many fields including medical, pharmaceutical, or material science. Due to their flexibility, proteins tend to respond to their environmental conditions and can undergo structural and conformational changes. For instance, alterations in physiological factors such as temperature, ions concentration, or pH as well as the adsorption to an interface can initiate protein aggregation. Therefore, at different surfaces and interfaces the characterization of the structural and colloidal stability of proteins, which is mainly influenced by their electrostatic and hydrophobic interactions, is of fundamental importance. In this study, we utilized sum frequency generation (SFG) spectroscopy to assess the role of solution pH on the polarity and magnitude of the electric field within the hydration shell of selected model proteins adsorbed to a hydrophobic surface. We used polystyrene (PS) as a model hydrophobic surface and determined the isoelectric point (IEP) of four structurally different model proteins. Comparing the measured IEP of proteins at the PS/solution or air/solution interface with that determined in the bulk solution via zeta potential measurement, we found significant similarities between the IEP of surface adsorbed proteins and those in the bulk aqueous phase. The pH dependence behavior of proteins was correlated to their amino acid composition and degree of hydrophobicity.
Collapse
Affiliation(s)
- Vanessa Lautenbach
- Institute of Particle Technology (LFG), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Saman Hosseinpour
- Institute of Particle Technology (LFG), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| |
Collapse
|
15
|
Wolf AT. Organofunktionelle Silane als Haftvermittler. CHEM UNSERER ZEIT 2021. [DOI: 10.1002/ciuz.202000054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
16
|
March D, Bianco V, Franzese G. Protein Unfolding and Aggregation near a Hydrophobic Interface. Polymers (Basel) 2021; 13:polym13010156. [PMID: 33401542 PMCID: PMC7795562 DOI: 10.3390/polym13010156] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 12/22/2020] [Accepted: 12/24/2020] [Indexed: 01/29/2023] Open
Abstract
The behavior of proteins near interfaces is relevant for biological and medical purposes. Previous results in bulk show that, when the protein concentration increases, the proteins unfold and, at higher concentrations, aggregate. Here, we study how the presence of a hydrophobic surface affects this course of events. To this goal, we use a coarse-grained model of proteins and study by simulations their folding and aggregation near an ideal hydrophobic surface in an aqueous environment by changing parameters such as temperature and hydrophobic strength, related, e.g., to ions concentration. We show that the hydrophobic surface, as well as the other parameters, affect both the protein unfolding and aggregation. We discuss the interpretation of these results and define future lines for further analysis, with their possible implications in neurodegenerative diseases.
Collapse
Affiliation(s)
- David March
- Secció de Física Estadística i Interdisciplinària—Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain;
| | - Valentino Bianco
- Chemical Physics Department, Faculty of Chemistry, Universidad Complutense de Madrid, Plaza de las Ciencias, Ciudad Universitaria, 28040 Madrid, Spain
- Correspondence: (V.B.); (G.F.)
| | - Giancarlo Franzese
- Secció de Física Estadística i Interdisciplinària—Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain;
- Correspondence: (V.B.); (G.F.)
| |
Collapse
|
17
|
Hong Y, Bao S, Xiang X, Wang X. Concentration-Dominated Orientation of Phenyl Groups at the Polystyrene/Graphene Interface. ACS Macro Lett 2020; 9:889-894. [PMID: 35648522 DOI: 10.1021/acsmacrolett.0c00279] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The interfacial orientation of aromatic groups plays a crucial role in determining the properties of graphene-based aromatic polymer nanocomposites. Here, the interfacial orientation of the polystyrene (PS) phenyl groups in contact with graphene is revealed by sum frequency generation (SFG) vibrational spectroscopy. The SFG spectra showed that the orientation of the phenyl groups is closely related to the interfacial concentration as the chains reach the quasi-equilibrium state. The phenyl groups remain in a relatively unrestricted state at a low concentration of the PS phenyl groups, and they prefer to recline to more favorably interact with graphene via a face-to-face configuration. Densely stacked phenyl groups are too crowded to form multilayer face-to-face interactions with graphene, and they prefer to remain upright, while π-π interactions are formed among the phenyl groups themselves in addition to the edge-to-face interactions to maximize the bonding energy of the π-π interactions. This is enthalpically favorable and driven mainly by the π-π interactions. This work provides important knowledge for the design and optimization of functional graphene-based aromatic polymer nanocomposites.
Collapse
Affiliation(s)
- Yongming Hong
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Senyang Bao
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Xiang Xiang
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Xinping Wang
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, China
| |
Collapse
|
18
|
Zhang C, Gao J, Hankett J, Varanasi P, Borst J, Shirazi Y, Zhao S, Chen Z. Corn Oil-Water Separation: Interactions of Proteins and Surfactants at Corn Oil/Water Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4044-4054. [PMID: 32212710 DOI: 10.1021/acs.langmuir.0c00338] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Purification and collection of industrial products from oil-water mixtures are commonly implemented processes. However, the efficiencies of such processes can be severely influenced by the presence of emulsifiers that induce the formation of small oil droplets dispersed in the mixtures. Understanding of this emulsifying effect and its counteractions which occur at the oil/water interface is therefore necessary for the improvement of designs of these processes. In this paper, we investigated the interfacial mechanisms of protein-induced emulsification and the opposing surfactant-induced demulsification related to corn oil refinement. At corn oil/water interfaces, the pH-dependent emulsifying function of zein protein, which is the major storage protein of corn, was elucidated by the surface/interface-sensitive sum frequency generation (SFG) vibrational spectroscopy technique. The effective stabilization of corn oil droplets by zein protein was illustrated and correlated to its ordered amide I group at the oil/water interface. Substantial decrease of this ordering with the addition of three industrial surfactants to corn oil-zein solution mixtures was also observed using SFG, which explains the surfactant-induced destabilization and coalescence of small oil droplets. Surfactant-protein interaction was then demonstrated to be the driving force for the disordering of interfacial proteins, either by disrupting protein layers or partially excluding protein molecules from the interface. The ordered zein proteins at the interface were therefore revealed to be the critical factor for the formation of corn oil-water emulsion.
Collapse
Affiliation(s)
- Chengcheng Zhang
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Jinpeng Gao
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Jeanne Hankett
- BASF Corporation, 1609 Biddle Avenue, Wyandotte, Michigan 48192, United States
| | - Prabodh Varanasi
- BASF Corporation, 1609 Biddle Avenue, Wyandotte, Michigan 48192, United States
| | - Joseph Borst
- BASF Corporation, 1609 Biddle Avenue, Wyandotte, Michigan 48192, United States
| | - Yaser Shirazi
- BASF Corporation, 1609 Biddle Avenue, Wyandotte, Michigan 48192, United States
| | - Shouxun Zhao
- BASF Corporation, 1609 Biddle Avenue, Wyandotte, Michigan 48192, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
19
|
Meesaragandla B, García I, Biedenweg D, Toro-Mendoza J, Coluzza I, Liz-Marzán LM, Delcea M. H-Bonding-mediated binding and charge reorganization of proteins on gold nanoparticles. Phys Chem Chem Phys 2020; 22:4490-4500. [DOI: 10.1039/c9cp06371d] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Gold nanoparticles with various functionalities interact with the human serum albumin (HSA) leading to protein structural changes. HSA-nanoparticles bioconjugates display lower toxicity and slower cell uptake rates, compared to nanoparticles in the absence of protein.
Collapse
Affiliation(s)
- Brahmaiah Meesaragandla
- Institute of Biochemistry
- University of Greifswald
- 17489 Greifswald
- Germany
- ZIK HIKE – Center for Innovation Competence “Humoral Immune Reactions in Cardiovascular Diseases”
| | - Isabel García
- CIC biomaGUNE and CIBER de Bioingeniería
- Biomateriales y Nanomedicina (CIBER-BBN)
- 20014 Donostia-San Sebastián
- Spain
| | - Doreen Biedenweg
- ZIK HIKE – Center for Innovation Competence “Humoral Immune Reactions in Cardiovascular Diseases”
- University of Greifswald
- 17489 Greifswald
- Germany
| | - Jhoan Toro-Mendoza
- CIC biomaGUNE and CIBER de Bioingeniería
- Biomateriales y Nanomedicina (CIBER-BBN)
- 20014 Donostia-San Sebastián
- Spain
| | - Ivan Coluzza
- CIC biomaGUNE and CIBER de Bioingeniería
- Biomateriales y Nanomedicina (CIBER-BBN)
- 20014 Donostia-San Sebastián
- Spain
- Ikerbasque
| | - Luis M. Liz-Marzán
- CIC biomaGUNE and CIBER de Bioingeniería
- Biomateriales y Nanomedicina (CIBER-BBN)
- 20014 Donostia-San Sebastián
- Spain
- Ikerbasque
| | - Mihaela Delcea
- Institute of Biochemistry
- University of Greifswald
- 17489 Greifswald
- Germany
- ZIK HIKE – Center for Innovation Competence “Humoral Immune Reactions in Cardiovascular Diseases”
| |
Collapse
|
20
|
Perera HAG, Lu T, Fu L, Zhang J, Chen Z. Probing the Interfacial Interactions of Monoclonal and Bispecific Antibodies at the Silicone Oil-Aqueous Solution Interface by Using Sum Frequency Generation Vibrational Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:14339-14347. [PMID: 31597425 DOI: 10.1021/acs.langmuir.9b02768] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Silicone oil has been widely utilized in the pharmaceutical industry especially as a lubricant coating commonly used in syringes for the smooth delivery of drugs. Protein structure perturbation and aggregation have been reported upon protein contacting silicone oil by using indirect methods and ex-situ techniques. The conclusions derived from such indirect and ex-situ methods may not truly reflect the exact nature of the protein-silicone oil interfacial interactions. Recently, we have successfully demonstrated that sum frequency generation (SFG) vibrational spectroscopy can be used as a powerful and direct method of studying the fusion protein-silicone oil interfacial interactions in situ and in real time. In this article, we studied monoclonal and bispecific antibody interactions with the silicone oil surface by using SFG spectroscopy. Being structurally and functionally different in the nature of fusion proteins and antibodies, this study is important in enhancing our current understanding of protein-silicone oil interfacial interactions. Both types of antibodies investigated here readily and strongly adsorb onto the silicone oil surface and remain stable at least for 10 h. SFG spectra in the amide I region for monoclonal and bispecific antibodies centered at 1660 and 1665 cm-1, respectively, suggest the difference in their molecular structures. The absence of the antibody signals in the amide I region of time-dependent and static SFG spectra obtained for preadsorbed antibodies onto silicone oil after contacting polysorbate 80 (PS-80) surfactant suggests that PS-80 can effectively remove both types of antibodies from the silicone oil surface. This study demonstrated the feasibility of using SFG spectroscopy as a powerful tool for probing the antibody-interfacial interactions in situ and in real time.
Collapse
Affiliation(s)
- H A Ganganath Perera
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Tieyi Lu
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Li Fu
- Sanofi , 1 The Mountain Road , Framingham , Massachusetts 01701 , United States
| | - Jifeng Zhang
- Sanofi , 1 The Mountain Road , Framingham , Massachusetts 01701 , United States
| | - Zhan Chen
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| |
Collapse
|
21
|
He Y, Zhang Y, Ren H, Wang J, Guo W, Sun SG, Wang Z. Abnormal spectral bands in broadband sum frequency generation induced by bulk absorption and refraction. OPTICS EXPRESS 2019; 27:28564-28574. [PMID: 31684606 DOI: 10.1364/oe.27.028564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 09/07/2019] [Indexed: 06/10/2023]
Abstract
In this paper, the time-resolved broadband sum frequency generation (BB-SFG) spectra from a bare Au surface with a distorted infrared (introduced with a 10 µm polyethylene film in the IR light path) and principal component generalized projection (PCGP) algorithm were used to investigate the bulk distortion on the measured BB-SFG spectra. Besides the SFG intensity reduction from the bulk absorption, the frequency dependent refraction of the bulk layer led to misleading SFG features at the positive delay times beyond the Au dephasing time. These results suggest that SFG spectroscopy is not entirely 'bulk-free' for the buried interfaces because of the bulk absorption and refraction of the incident pulses.
Collapse
|
22
|
Ge A, Qiao L, Seo JH, Yui N, Ye S. Surface-Restructuring Differences between Polyrotaxanes and Random Copolymers in Aqueous Environment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:12463-12470. [PMID: 30216076 DOI: 10.1021/acs.langmuir.8b02676] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In the present study, we investigated the surface reorganization behaviors and adsorption conformations of fibrinogen on the surface of polyrotaxanes containing different amounts of α-cyclodextrin (α-CD) by using surface-sensitive vibrational spectroscopy sum frequency generation (SFG). For comparison, behaviors of the surface restructuring and fibrinogen adsorption on the random copolymers containing similar terminal groups were also investigated. It was found that larger amounts of BMA moieties of polyrotaxanes form ordered surface structures after immersion in water for 48 h. Furthermore, the polyrotaxane surfaces exhibit a much higher capability of fibrinogen adsorption than the random copolymer surfaces. The water-induced surface restructuring of the polyrotaxane films slightly affects the adsorption structure of the fibrinogen molecules.
Collapse
Affiliation(s)
- Aimin Ge
- Institute for Catalysis , Hokkaido University , Sapporo 001-0021 , Japan
| | - Lin Qiao
- Institute for Catalysis , Hokkaido University , Sapporo 001-0021 , Japan
| | - Ji-Hun Seo
- Institute of Biomaterials and Bioengineering , Tokyo Medical and Dental University , Tokyo 101-0062 , Japan
| | - Nobuhiko Yui
- Institute of Biomaterials and Bioengineering , Tokyo Medical and Dental University , Tokyo 101-0062 , Japan
| | - Shen Ye
- Department of Chemistry, Graduate School of Science , Tohoku University , Sendai 980-8578 , Japan
| |
Collapse
|
23
|
Dhopatkar N, Anim-Danso E, Peng C, Singla S, Liu X, Joy A, Dhinojwala A. Reorganization of an Amphiphilic Glassy Polymer Surface in Contact with Water Probed by Contact Angle and Sum Frequency Generation Spectroscopy. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00640] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nishad Dhopatkar
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States
| | - Emmanuel Anim-Danso
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States
| | - Chao Peng
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States
| | - Saranshu Singla
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States
| | - Xinhao Liu
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States
| | - Abraham Joy
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States
| | - Ali Dhinojwala
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States
| |
Collapse
|
24
|
Xiao M, Mohler C, Tucker C, Walther B, Lu X, Chen Z. Structures and Adhesion Properties at Polyethylene/Silica and Polyethylene/Nylon Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:6194-6204. [PMID: 29716190 DOI: 10.1021/acs.langmuir.8b00930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The molecular structures of buried interfaces of maleic anhydride grafted and ungrafted polyethylene films with silica and nylon surfaces were studied in situ using sum-frequency generation (SFG) vibrational spectroscopy. Grafting maleic anhydride to polyethylene altered the molecular structures at buried interfaces, including changing the orientation of polymer methylene groups and resulting in the presence of C═O groups at silica interfaces. These molecular level changes are correlated with enhanced adhesion properties, with ordered C═O groups and in-plane orientation of the methylene groups associated with higher levels of adhesion. While improved adhesion was observed for grafted polyethylene at the nylon interface, no C═O groups were detected at the interface using SFG, for films thermally treated at 185 °C. In this case, either no C═O groups are present at the interface or they are disordered; the latter explanation is more likely, considering the observed improvement in adhesion.
Collapse
Affiliation(s)
- Minyu Xiao
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Carol Mohler
- Core R&D-Formulation Science , The Dow Chemical Company , Midland , Michigan 48674 , United States
| | - Christopher Tucker
- Core R&D-Formulation Science , The Dow Chemical Company , Midland , Michigan 48674 , United States
| | - Brian Walther
- Packaging & Specialty Plastics TS&D F&SP , The Dow Chemical Company , Freeport , Texas 77541 , United States
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering , Southeast University , Nanjing 210096 , China
| | - Zhan Chen
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| |
Collapse
|
25
|
Reitböck C, Głowacki E, Stifter D. Sum-Frequency Generation Vibrational Spectroscopy Investigations of Phosphonic Acids on Anodic Aluminum Oxide Films. APPLIED SPECTROSCOPY 2018; 72:725-730. [PMID: 29436845 DOI: 10.1177/0003702818756899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Self-assembled monolayers of alkyl phosphonic acids on anodic aluminum oxide (AlOx) surfaces are important as dielectric layers in thin film electronic devices. Assessing the properties and quality of these monolayers on amorphous AlOx is limited to a few surface-sensitive methods. In this work, we study using nonlinear optical measurements the molecular ordering in n-alkyl phosphonic acids with various alkyl chain lengths (6 to 18 carbons) deposited on AlOx and show the influence of temperature on stability and conformational order. The results demonstrate that the octadecylphosphonic acid has fewest defects in the chain orientation. A detailed comparison of the longest and the shortest alkyl chain revealed different behavior in conformational ordering upon annealing.
Collapse
Affiliation(s)
- Cornelia Reitböck
- 1 Center for Surface- and Nanoanalytics, Johannes Kepler University Linz, Linz, Austria
| | - Eric Głowacki
- 2 101031 Laboratory of Organic Electronics, ITN, Campus Norrköping, Linköping University, Norrköping, Sweden
| | - David Stifter
- 1 Center for Surface- and Nanoanalytics, Johannes Kepler University Linz, Linz, Austria
| |
Collapse
|
26
|
Streubel S, Schulze-Zachau F, Weißenborn E, Braunschweig B. Ion Pairing and Adsorption of Azo Dye/C 16TAB Surfactants at the Air-Water Interface. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:27992-28000. [PMID: 29285205 PMCID: PMC5742476 DOI: 10.1021/acs.jpcc.7b08924] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 10/29/2017] [Indexed: 06/01/2023]
Abstract
Mixed layers of 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate (Sunset Yellow, SSY) and cetyltrimethylammonium bromide (C16TAB) at the air-water interface were studied using vibrational sum-frequency generation (SFG) and dynamic surface tension measurements. In the bulk, addition of C16TAB to SSY aqueous solution causes substantial changes in UV/vis absorption spectra, which originate from strong electrostatic interactions between the anionic SSY azo dye with the cationic C16TAB surfactant. These interactions are a driving force for the formation of SSY/C16TAB ion pairs. The latter are found to be highly surface active while free SSY molecules show no surface activity. Dynamic SFG as well as surface tension measurements at low SSY concentrations reveal that free C16TAB surfactants adsorb at the air-water interface on time scales <1 s where they initially form the dominating surface species, but on longer time scales free C16TAB is exchanged by SSY/C16TAB ion pairs. This causes a dramatic reduction of the surface tension to 35 mN/m but also in foam stability. These changes are accompanied by a substantial loss in SFG intensity from O-H stretching bands around 3200 and 3450 cm-1, which we relate to a decrease in surface charging due to adsorption of ion pairs with no or negligible net charges. For SSY/C16TAB molar ratios >0.5, the O-H bands in SFG spectra are reduced to very low intensities and are indicative to electrically neutral SSY/C16TAB ion pairs. This conclusion is corroborated by an analysis of macroscopic foams, which become highly instable in the presence of neutral SSY/C16TAB ion pairs. From an analysis of SFG spectra of air-water interfaces, we show that the electrostatic repulsion forces inside the ubiquitous foam films are reduced and thus remove the major stabilization mechanism within macroscopic foam.
Collapse
Affiliation(s)
- Saskia Streubel
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Felix Schulze-Zachau
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Eric Weißenborn
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Björn Braunschweig
- Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| |
Collapse
|
27
|
Zhang C. Sum Frequency Generation Vibrational Spectroscopy for Characterization of Buried Polymer Interfaces. APPLIED SPECTROSCOPY 2017; 71:1717-1749. [PMID: 28537432 DOI: 10.1177/0003702817708321] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Sum frequency generation vibrational spectroscopy (SFG-VS) has become one of the most appealing technologies to characterize molecular structures at interfaces. In this focal point review, we focus on SFG-VS studies at buried polymer interfaces and review many of the recent publications in the field. We also cover the essential theoretical background of SFG-VS and discuss the experimental implementation of SFG-VS.
Collapse
Affiliation(s)
- Chi Zhang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| |
Collapse
|
28
|
Schmüser L, Roeters S, Lutz H, Woutersen S, Bonn M, Weidner T. Determination of Absolute Orientation of Protein α-Helices at Interfaces Using Phase-Resolved Sum Frequency Generation Spectroscopy. J Phys Chem Lett 2017; 8:3101-3105. [PMID: 28605589 DOI: 10.1021/acs.jpclett.7b01059] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Understanding the structure of proteins at surfaces is key in fields such as biomaterials research, biosensor design, membrane biophysics, and drug design. A particularly important factor is the orientation of proteins when bound to a particular surface. The orientation of the active site of enzymes or protein sensors and the availability of binding pockets within membrane proteins are important design parameters for engineers developing new sensors, surfaces, and drugs. Recently developed methods to probe protein orientation, including immunoessays and mass spectrometry, either lack structural resolution or require harsh experimental conditions. We here report a new method to track the absolute orientation of interfacial proteins using phase-resolved sum frequency generation spectroscopy in combination with molecular dynamics simulations and theoretical spectral calculations. As a model system we have determined the orientation of a helical lysine-leucine peptide at the air-water interface. The data show that the absolute orientation of the helix can be reliably determined even for orientations almost parallel to the surface.
Collapse
Affiliation(s)
- Lars Schmüser
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research , 55128 Mainz, Germany
| | - Steven Roeters
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam , 1098 EP Amsterdam, The Netherlands
| | - Helmut Lutz
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research , 55128 Mainz, Germany
| | - Sander Woutersen
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam , 1098 EP Amsterdam, The Netherlands
| | - Mischa Bonn
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research , 55128 Mainz, Germany
| | - Tobias Weidner
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research , 55128 Mainz, Germany
- Department of Chemistry, Aarhus University , 8000 Aarhus C, Denmark
| |
Collapse
|
29
|
Schulze-Zachau F, Braunschweig B. Structure of Polystyrenesulfonate/Surfactant Mixtures at Air-Water Interfaces and Their Role as Building Blocks for Macroscopic Foam. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3499-3508. [PMID: 28318264 PMCID: PMC5391498 DOI: 10.1021/acs.langmuir.7b00400] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/17/2017] [Indexed: 05/26/2023]
Abstract
Air/water interfaces were modified by oppositely charged poly(sodium 4-styrenesulfonate) (NaPSS) and hexadecyltrimethylammonium bromide (CTAB) polyelectrolyte/surfactant mixtures and were studied on a molecular level with vibrational sum-frequency generation (SFG), tensiometry, surface dilatational rheology and ellipsometry. In order to deduce structure property relations, our results on the interfacial molecular structure and lateral interactions of PSS-/CTA+ complexes were compared to the stability and structure of macroscopic foam as well as to bulk properties. For that, the CTAB concentration was fixed to 0.1 mM, while the NaPSS concentration was varied. At NaPSS monomer concentrations <0.1 mM, PSS-/CTA+ complexes start to replace free CTA+ surfactants at the interface and thus reduce the interfacial electric field in the process. This causes the O-H bands from interfacial H2O molecules in our SFG spectra to decrease substantially, which reach a local minimum in intensity close to equimolar concentrations. Once electrostatic repulsion is fully screened at the interface, hydrophobic PSS-/CTA+ complexes dominate and tend to aggregate at the interface and in the bulk solution. As a consequence, adsorbate layers with the highest film thickness, surface pressure, and dilatational elasticity are formed. These surface layers provide much higher stabilities and foamabilities of polyhedral macroscopic foams. Mixtures around this concentration show precipitation after a few days, while their surfaces to air are in a local equilibrium state. Concentrations >0.1 mM result in a significant decrease in surface pressure and a complete loss in foamability. However, SFG and surface dilatational rheology provide strong evidence for the existence of PSS-/CTA+ complexes at the interface. At polyelectrolyte concentrations >10 mM, air-water interfaces are dominated by an excess of free PSS- polyelectrolytes and small amounts of PSS-/CTA+ complexes which, however, provide higher foam stabilities compared to CTAB free foams. The foam structure undergoes a transition from wet to polyhedral foams during the collapse.
Collapse
Affiliation(s)
- Felix Schulze-Zachau
- Institute
of Physical Chemistry, Westfälische
Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
- Erlangen
Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg
(FAU), Paul-Gordan-Strasse
6, 91052 Erlangen, Germany
| | - Björn Braunschweig
- Institute
of Physical Chemistry, Westfälische
Wilhelms-Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| |
Collapse
|
30
|
Wang W, Ye S. Molecular interactions of organic molecules at the air/water interface investigated by sum frequency generation vibrational spectroscopy. Phys Chem Chem Phys 2017; 19:4488-4493. [PMID: 28120952 DOI: 10.1039/c6cp07827c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The molecular structure and dynamics of organic molecules at the aqueous interface have attracted a number of investigations owing to their importance and specific nature. However, there are relatively few studies on the direct characterization of the molecular interactions at the air/water interface because they are extremely difficult to measure in experiments. In this study, we use dibutyl ester molecules (R1CO2R2O2CR1) as a model of organic molecules, and investigate their molecular structure and interactions using sum frequency generation vibrational spectroscopy. We demonstrate that the molecular interactions can be estimated by measuring the intensity ratio of the symmetric stretching (ν1) and Fermi resonant bands (2ν2) of methyl groups. Here, dibutyl ester molecules are widely used as plasticizers in polymers to improve the properties of the plastics and polymers. It is found that the orientation angles of the tailed methyl groups at the air/water interface decrease from 34° to 19° when the chain length of R2 increases from 0 to 8. The total intermolecular interactions of the dibutyl ester molecules decrease as the chain length of R2 increases because the van der Waals interactions between the hydrocarbon chains increase, while the hydrogen bond interactions between the carbonyl group and water molecules decrease. Our study demonstrates the stability of ester-based plasticizers in polymers can be well predicted from the intensity ratio of the ν1 and 2ν2 bands of methyl group. Such an intensity ratio can be thus used as an effective vibrational optical ruler for characterizing molecular interactions between plasticizers and polymers.
Collapse
Affiliation(s)
- Wenting Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China. and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shuji Ye
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China. and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| |
Collapse
|
31
|
Lu X, Zhang C, Ulrich N, Xiao M, Ma YH, Chen Z. Studying Polymer Surfaces and Interfaces with Sum Frequency Generation Vibrational Spectroscopy. Anal Chem 2016; 89:466-489. [DOI: 10.1021/acs.analchem.6b04320] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Xiaolin Lu
- State
Key Laboratory of Bioelectronics, School of Biological Science and
Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
| | - Chi Zhang
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Nathan Ulrich
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Minyu Xiao
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Yong-Hao Ma
- State
Key Laboratory of Bioelectronics, School of Biological Science and
Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
| | - Zhan Chen
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
32
|
Leng C, Sun S, Zhang K, Jiang S, Chen Z. Molecular level studies on interfacial hydration of zwitterionic and other antifouling polymers in situ. Acta Biomater 2016; 40:6-15. [PMID: 26923530 DOI: 10.1016/j.actbio.2016.02.030] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 01/19/2016] [Accepted: 02/22/2016] [Indexed: 12/16/2022]
Abstract
UNLABELLED Antifouling polymers have wide applications in biomedical engineering and marine industry. Recently, zwitterionic materials have been reported as promising candidates for antifouling applications, while strong hydration is believed to be the key antifouling mechanism. Zwitterionic materials can be designed with various molecular structures, which affect their hydration and antifouling performance. Although strong hydration has been proposed to occur at the material surfaces, probing the solid material/water interfaces is challenging with traditional analytical techniques. Here in this review, we will review our studies on surface hydration of zwitterionic materials and other antifouling materials by using sum frequency generation (SFG) vibrational spectroscopy, which provides molecular understanding of the water structures at various material surfaces. The materials studied include zwitterionic polymer brushes with different molecular structures, amphiphilic polymers with zwitterionic groups, uncharged hydrophilic polymer brushes, amphiphilic polypeptoids, and widely used antifouling material poly(ethylene glycol). We will compare the differences among zwitterionic materials with various molecular structures as well as the differences between antifouling materials and fouling surfaces of control samples. We will also discuss the effects of pH and biological molecules like proteins on the surface hydration of the zwitterionic materials. Using SFG spectroscopy, we have measured the hydration layers of antifouling materials and found that strong hydrogen bonds are key to the formation of strong hydration layers preventing protein fouling at the polymer interfaces. STATEMENT OF SIGNIFICANCE Antifouling polymers have wide applications in biomedical engineering and marine industry. Recently, zwitterionic materials have been reported as promising candidates for antifouling applications, while strong hydration is believed to be the key antifouling mechanism. However, zwitterionic materials can be designed with various molecular structures, which affect their hydration and antifouling performance. Moreover, although strong hydration has been proposed to occur at the material surfaces, probing the solid material/water interfaces is challenging with traditional analytical techniques. Here in this manuscript, we will review our studies on surface hydration of zwitterionic materials and other antifouling materials by using sum frequency generation (SFG) vibrational spectroscopy, which provides molecular understanding of the water structures at various material surfaces. The materials studied include zwitterionic polymer brushes with different molecular structures, amphiphilic polymers with zwitterionic groups, uncharged hydrophilic polymer brushes, amphiphilic polypeptoids, and widely used antifouling material poly(ethylene glycol). We will compare the differences among zwitterionic materials with various molecular structures as well as the differences between antifouling materials and fouling surfaces of control samples. We will also discuss the effects of pH and biological molecules like proteins on the surface hydration of the zwitterionic materials. All the SFG results indicate that strongly hydrogen-bonded water at the materials' surfaces (strong surface hydration) is closely correlated to the good antifouling properties of the materials. This review will be widely interested by readers of Acta Biomaterialia and will impact many different research fields in chemistry, materials, engineering, and beyond.
Collapse
|
33
|
Braunschweig B, Schulze-Zachau F, Nagel E, Engelhardt K, Stoyanov S, Gochev G, Khristov K, Mileva E, Exerowa D, Miller R, Peukert W. Specific effects of Ca(2+) ions and molecular structure of β-lactoglobulin interfacial layers that drive macroscopic foam stability. SOFT MATTER 2016; 12:5995-6004. [PMID: 27337699 PMCID: PMC5048339 DOI: 10.1039/c6sm00636a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 06/12/2016] [Indexed: 06/01/2023]
Abstract
β-Lactoglobulin (BLG) adsorption layers at air-water interfaces were studied in situ with vibrational sum-frequency generation (SFG), tensiometry, surface dilatational rheology and ellipsometry as a function of bulk Ca(2+) concentration. The relation between the interfacial molecular structure of adsorbed BLG and the interactions with the supporting electrolyte is additionally addressed on higher length scales along the foam hierarchy - from the ubiquitous air-water interface through thin foam films to macroscopic foam. For concentrations <1 mM, a strong decrease in SFG intensity from O-H stretching bands and a slight increase in layer thickness and surface pressure are observed. A further increase in Ca(2+) concentrations above 1 mM causes an apparent change in the polarity of aromatic C-H stretching vibrations from interfacial BLG which we associate to a charge reversal at the interface. Foam film measurements show formation of common black films at Ca(2+) concentrations above 1 mM due to considerable decrease of the stabilizing electrostatic disjoining pressure. These observations also correlate with a minimum in macroscopic foam stability. For concentrations >30 mM Ca(2+), micrographs of foam films show clear signatures of aggregates which tend to increase the stability of foam films. Here, the interfacial layers have a higher surface dilatational elasticity. In fact, macroscopic foams formed from BLG dilutions with high Ca(2+) concentrations where aggregates and interfacial layers with higher elasticity are found, showed the highest stability with much smaller bubble sizes.
Collapse
Affiliation(s)
- Björn Braunschweig
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany. and Cluster of Excellence Engineering of Advanced Materials (EAM), Nägelsbachstr. 49b, 91052 Erlangen, Germany and Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052 Erlangen, Germany and Interdisciplinary Center of Functional Particle Systems, Haberstraße 9a, 91058 Erlangen, Germany
| | - Felix Schulze-Zachau
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany. and Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052 Erlangen, Germany and Interdisciplinary Center of Functional Particle Systems, Haberstraße 9a, 91058 Erlangen, Germany
| | - Eva Nagel
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany.
| | - Kathrin Engelhardt
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany.
| | - Stefan Stoyanov
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Georgi Gochev
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria and Max-Planck-Institute of Colloids and Interfaces, 14476 Golm/Potsdam, Germany
| | - Khr Khristov
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Elena Mileva
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Dotchi Exerowa
- Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Reinhard Miller
- Max-Planck-Institute of Colloids and Interfaces, 14476 Golm/Potsdam, Germany
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany. and Cluster of Excellence Engineering of Advanced Materials (EAM), Nägelsbachstr. 49b, 91052 Erlangen, Germany and Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052 Erlangen, Germany and Interdisciplinary Center of Functional Particle Systems, Haberstraße 9a, 91058 Erlangen, Germany
| |
Collapse
|
34
|
Xiao M, Jasensky J, Zhang X, Li Y, Pichan C, Lu X, Chen Z. Influence of the side chain and substrate on polythiophene thin film surface, bulk, and buried interfacial structures. Phys Chem Chem Phys 2016; 18:22089-99. [DOI: 10.1039/c6cp04155h] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We elucidated the effects of the polythiophene side chain and the substrate surface hydrophobicity on polythiophene thin film–substrate interfacial interactions; such interactions influence the interfacial structure, bulk film structure, and the surface structure.
Collapse
Affiliation(s)
- Minyu Xiao
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| | | | - Xiaoxian Zhang
- Key laboratory of Standardization and Measurement for Nanotechnology
- Chinese Academy of Sciences
- National Center for Nanoscience and Technology
- Beijing 100190
- China
| | - Yaoxin Li
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| | - Cayla Pichan
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics
- School of Biological Science and Medical Engineering
- Southeast University
- Nanjing 210096
- China
| | - Zhan Chen
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| |
Collapse
|
35
|
Ge A, Seo JH, Qiao L, Yui N, Ye S. Structural Reorganization and Fibrinogen Adsorption Behaviors on the Polyrotaxane Surfaces Investigated by Sum Frequency Generation Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2015; 7:22709-22718. [PMID: 26393413 DOI: 10.1021/acsami.5b07760] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Polyrotaxanes, such as supramolecular assemblies with methylated α-cyclodextrins (α-CDs) as host molecules noncovalently threaded on the linear polymer backbone, are promising materials for biomedical applications because they allow adsorbed proteins possessing a high surface flexibility as well as control of the cellular morphology and adhesion. To provide a general design principle for biomedical materials, we examined the surface reorganization behaviors and adsorption conformations of fibrinogen on the polyrotaxane surfaces with comparison to several random copolymers by sum frequency generation (SFG) vibrational spectroscopy. We showed that the polyrotaxane (OMe-PRX-PMB) with methylated α-CDs as the host molecule exhibited unique surface structures in an aqueous environment. The hydrophobic interaction between the methoxy groups of the methylated α-CD molecules and methyl groups of the n-butyl methacrylate (BMA) side chains may dominate the surface restructuring behavior of the OMe-PRX-PMB. The orientation analysis revealed that the orientation of the fibrinogen adsorbed on the OMe-PRX-PMB surface is close to a single distribution, which is different from the adsorption behaviors of fibrinogen on other polyrotaxane or random copolymer surfaces.
Collapse
Affiliation(s)
- Aimin Ge
- Catalysis Research Center, Hokkaido University , Sapporo 001-0021, Japan
| | - Ji-Hun Seo
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University , Tokyo 101-0062, Japan
| | - Lin Qiao
- Catalysis Research Center, Hokkaido University , Sapporo 001-0021, Japan
| | - Nobuhiko Yui
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University , Tokyo 101-0062, Japan
| | - Shen Ye
- Catalysis Research Center, Hokkaido University , Sapporo 001-0021, Japan
| |
Collapse
|
36
|
Leng C, Buss HG, Segalman RA, Chen Z. Surface Structure and Hydration of Sequence-Specific Amphiphilic Polypeptoids for Antifouling/Fouling Release Applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:9306-11. [PMID: 26245923 DOI: 10.1021/acs.langmuir.5b01440] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Amphiphilic polypeptoids can be designed with specific sequences of hydrophilic and hydrophobic units, which determine their surface properties for antifouling/fouling release purposes. Although the sequence-dependent surface structures of polypeptoids have been extensively investigated, e.g., with X-ray spectroscopy, their molecular structures under the aqueous conditions relevant to marine fouling have not been studied. In this work, we applied sum frequency generation (SFG) vibrational spectroscopy to study the surface structures and hydration of a series of amphiphilic polypeptoid coatings with different sequences in air and water. SFG spectra, in agreement with X-ray spectroscopy studies, revealed that the surface coverage of the hydrophilic N-(2-methoxyethyl)glycine (Nme) units in air is affected by both the number and position of the hydrophobic N-(heptafluorobutyl)glycine (NF) units in the peptoid chain and is negatively correlated with the surface concentration of the fluorine element. Our ability to probe the SFG signals of water molecules at the peptoid surface provides new information on the hydrated film properties. From these SFG signals and the time evolution of water contact angles on the polymers, we see that the hydrated film properties are also dependent upon the peptoid sequence. This work indicates that the surface presence of the Nme groups and the ability of the polymers to order and strongly hydrogen bond with interfacial water molecules determine their antifouling properties, whereas the surface restructuring rate upon contact with water affects their fouling release behaviors.
Collapse
Affiliation(s)
- Chuan Leng
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Hilda G Buss
- Department of Chemical Engineering, University of California , Berkeley, California 94720, United States
| | - Rachel A Segalman
- Departments of Materials and Chemical Engineering, University of California , Santa Barbara, California 93106, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| |
Collapse
|
37
|
Zhang C, Jasensky J, Chen Z. Multireflection Sum Frequency Generation Vibrational Spectroscopy. Anal Chem 2015; 87:8157-64. [DOI: 10.1021/acs.analchem.5b00641] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chi Zhang
- Departments of †Chemistry and ‡Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Joshua Jasensky
- Departments of †Chemistry and ‡Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Zhan Chen
- Departments of †Chemistry and ‡Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
38
|
Xiao M, Zhang X, Bryan ZJ, Jasensky J, McNeil AJ, Chen Z. Effect of Solvent on Surface Ordering of Poly(3-hexylthiophene) Thin Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:5050-5056. [PMID: 25876733 DOI: 10.1021/la5048722] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Enhancement of charge transport in organic polymer semiconductors is a crucial step in developing optimized devices. A variety of sample preparation conditions, such as film fabrication method, solvent species, and annealing, were found to influence the hole mobility of organic polymers. Despite the fact that many factors can influence their performance, it is believed that polymer surface ordering plays a key role in determining organic polymer function. Here, sum frequency generation (SFG) vibrational spectroscopy was used to nondestructively map the surface/interfacial ordering of poly(3-hexylthiophene) (P3HT) films prepared using different solvents; we believe that solvent interactions determine the degree of surface/interfacial ordering. Both X-ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM) were used to supplement SFG to systematically study bulk crystallinity and surface morphology. We conclude that SFG is a powerful tool to elucidate the surface/interfacial structural information on polymer semiconducting films. We demonstrate that the solvent composition used to prepare P3HT thin films influences the resulting film surface morphology, surface/interfacial ordering, and bulk crystallinity.
Collapse
Affiliation(s)
- Minyu Xiao
- †Department of Chemistry and ‡Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Xiaoxian Zhang
- †Department of Chemistry and ‡Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Zachary J Bryan
- †Department of Chemistry and ‡Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Joshua Jasensky
- †Department of Chemistry and ‡Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Anne J McNeil
- †Department of Chemistry and ‡Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Zhan Chen
- †Department of Chemistry and ‡Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| |
Collapse
|
39
|
Zhang C, Wang J, Jasensky J, Chen Z. Molecular Orientation Analysis of Alkyl Methylene Groups from Quantitative Coherent Anti-Stokes Raman Scattering Spectroscopy. J Phys Chem Lett 2015; 6:1369-1374. [PMID: 26263137 DOI: 10.1021/acs.jpclett.5b00394] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Quantitative data analysis in coherent anti-Stokes Raman scattering (CARS) spectroscopy is important for extracting molecular structural information. We developed a method to derive molecular tilt angle with respect to the surface normal based on quantitative CARS spectral analysis. We showed that the tilt angle of methylene alkyl chains on a surface can be directly obtained from the CH2 symmetric/asymmetric peak ratio in a CARS spectrum. The lipid alkyl chain tilt angle from a lipid monolayer was measured to be ∼0° and was verified by sum frequency generation spectroscopy, which probes the orientations of the lipid methyl end groups. The tilt angle of a silane monolayer alkyl chain was derived to be ∼35°, which agrees with the theoretical prediction. This method is submonolayer sensitive and can also be used to interpret polarization-dependent signals in CARS microscopy. It can be applied to elucidate detailed molecular structure from CARS spectroscopic and microscopic measurements.
Collapse
Affiliation(s)
- Chi Zhang
- †Department of Chemistry, and ‡Department of Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Jie Wang
- †Department of Chemistry, and ‡Department of Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Joshua Jasensky
- †Department of Chemistry, and ‡Department of Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Zhan Chen
- †Department of Chemistry, and ‡Department of Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
40
|
Myers JN, Chen Z. Surface plasma treatment effects on the molecular structure at polyimide/air and buried polyimide/epoxy interfaces. CHINESE CHEM LETT 2015. [DOI: 10.1016/j.cclet.2015.01.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
|
41
|
Myers JN, Zhang X, Bielefeld J, Lin Q, Chen Z. Nondestructive in Situ Characterization of Molecular Structures at the Surface and Buried Interface of Silicon-Supported Low-k Dielectric Films. J Phys Chem B 2015; 119:1736-46. [DOI: 10.1021/jp510205u] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- John N. Myers
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Xiaoxian Zhang
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Jeff Bielefeld
- Intel Corporation, Hillsboro, Oregon 97124, United States
| | - Qinghuang Lin
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - Zhan Chen
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
42
|
Ge A, Peng Q, Qiao L, Yepuri NR, Darwish TA, Matsusaki M, Akashi M, Ye S. Molecular orientation of organic thin films on dielectric solid substrates: a phase-sensitive vibrational SFG study. Phys Chem Chem Phys 2015; 17:18072-8. [DOI: 10.1039/c5cp02702k] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Phase-sensitive SFG spectroscopy is employed to determine the absolute molecular orientation on the solid/air and solid/liquid interfaces.
Collapse
Affiliation(s)
- Aimin Ge
- Catalysis Research Center
- Hokkaido University
- Sapporo 001-0021
- Japan
| | - Qiling Peng
- Catalysis Research Center
- Hokkaido University
- Sapporo 001-0021
- Japan
| | - Lin Qiao
- Catalysis Research Center
- Hokkaido University
- Sapporo 001-0021
- Japan
| | - Nageshwar R. Yepuri
- National Deuteration Facility
- Australian Nuclear Science and Technology Organization (ANSTO)
- Kirrawee DC
- Australia
| | - Tamim A. Darwish
- National Deuteration Facility
- Australian Nuclear Science and Technology Organization (ANSTO)
- Kirrawee DC
- Australia
| | - Michiya Matsusaki
- Department of Applied Chemistry
- Graduate School of Engineering
- Osaka University
- Osaka 565-0871
- Japan
| | - Mitsuru Akashi
- Department of Applied Chemistry
- Graduate School of Engineering
- Osaka University
- Osaka 565-0871
- Japan
| | - Shen Ye
- Catalysis Research Center
- Hokkaido University
- Sapporo 001-0021
- Japan
| |
Collapse
|
43
|
Hu P, Zhang X, Zhang C, Chen Z. Molecular interactions between gold nanoparticles and model cell membranes. Phys Chem Chem Phys 2015; 17:9873-84. [DOI: 10.1039/c5cp00477b] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Direct observations of the lipid flip-flop induced by Au NP – model mammalian cell membrane interactions.
Collapse
Affiliation(s)
- Peipei Hu
- Department of Chemistry
- University of Michigan
- Michigan 48109
- USA
| | - Xiaoxian Zhang
- Department of Chemistry
- University of Michigan
- Michigan 48109
- USA
| | - Chi Zhang
- Department of Chemistry
- University of Michigan
- Michigan 48109
- USA
| | - Zhan Chen
- Department of Chemistry
- University of Michigan
- Michigan 48109
- USA
| |
Collapse
|
44
|
Zhang X, Myers JN, Lin Q, Bielefeld JD, Chen Z. Probing the molecular structures of plasma-damaged and surface-repaired low-k dielectrics. Phys Chem Chem Phys 2015; 17:26130-9. [DOI: 10.1039/c5cp03649f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A comprehensive characterization on the plasma-damaged and silylation-repaired low-k dielectrics was demonstrated here at the molecular level.
Collapse
Affiliation(s)
- Xiaoxian Zhang
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| | - John N. Myers
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| | | | | | - Zhan Chen
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| |
Collapse
|
45
|
Bellani S, Porro M, Caddeo C, Saba MI, Miranda PB, Mattoni A, Lanzani G, Antognazza MR. The study of polythiophene/water interfaces by sum-frequency generation spectroscopy and molecular dynamics simulations. J Mater Chem B 2015; 3:6429-6438. [DOI: 10.1039/c5tb00388a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Polythiophene/water interfaces are investigated by sum frequency generation spectroscopy and molecular dynamics simulations, showing a preferential edge-on molecular orientation.
Collapse
Affiliation(s)
- S. Bellani
- Politecnico di Milano
- Dip.to di Fisica
- 20133 Milano
- Italy
- Center for Nano Science and Technology@PoliMi
| | - M. Porro
- Center for Nano Science and Technology@PoliMi
- Istituto Italiano di Tecnologia
- 20133 Milano
- Italy
- Politecnico di Milano
| | - C. Caddeo
- Istituto Officina dei Materiali CNR-IOM SLACS Cagliari
- Monserrato
- Italy
| | - M. I. Saba
- Istituto Officina dei Materiali CNR-IOM SLACS Cagliari
- Monserrato
- Italy
| | - P. B. Miranda
- Instituto de Fisica de Sao Carlos
- Universidade de Sao Paulo
- Sao Carlos
- Brazil
| | - A. Mattoni
- Istituto Officina dei Materiali CNR-IOM SLACS Cagliari
- Monserrato
- Italy
| | - G. Lanzani
- Politecnico di Milano
- Dip.to di Fisica
- 20133 Milano
- Italy
- Center for Nano Science and Technology@PoliMi
| | - M. R. Antognazza
- Center for Nano Science and Technology@PoliMi
- Istituto Italiano di Tecnologia
- 20133 Milano
- Italy
| |
Collapse
|
46
|
Zhang X, Li Y, Hankett JM, Chen Z. The molecular interfacial structure and plasticizer migration behavior of “green” plasticized poly(vinyl chloride). Phys Chem Chem Phys 2015; 17:4472-82. [DOI: 10.1039/c4cp05287k] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Both oxygen and argon plasma treatment made TBAC–PVC surfaces hydrophilic, but that of argon enhanced the migration of TBAC to water.
Collapse
Affiliation(s)
- Xiaoxian Zhang
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| | - Yaoxin Li
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| | | | - Zhan Chen
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| |
Collapse
|
47
|
Zhang X, Myers JN, Bielefeld JD, Lin Q, Chen Z. In situ observation of water behavior at the surface and buried interface of a low-k dielectric film. ACS APPLIED MATERIALS & INTERFACES 2014; 6:18951-18961. [PMID: 25313691 DOI: 10.1021/am504833v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Water adsorption in porous low-k dielectrics has become a significant challenge for both back-end-of-line integration and reliability. A simple method is proposed here to achieve in situ observation of water structure and water-induced structure changes at the poly(methyl silsesquioxane) (PMSQ) surface and the PMSQ/solid buried interface at the molecular level by combining sum frequency generation (SFG) vibrational spectroscopic and Fourier transform infrared (FTIR) spectroscopic studies. First, in situ SFG investigations of water uptake were performed to provide direct evidence that water diffuses predominantly along the PMSQ/solid interface rather than through the bulk. Furthermore, SFG experiments were conducted at the PMSQ/water interface to simulate water behavior at the pore inner surfaces for porous low-k materials. Water molecules were found to form strong hydrogen bonds at the PMSQ surface, while weak hydrogen bonding was observed in the bulk. However, both strongly and weakly hydrogen bonded water components were detected at the PMSQ/SiO2 buried interface. This suggests that the water structures at PMSQ/solid buried interfaces are also affected by the nature of solid substrate. Moreover, the orientation of the Si-CH3 groups at the buried interface was permanently changed by water adsorption, which might due to low flexibility of Si-CH3 groups at the buried interface. In brief, this study provides direct evidence that water molecules tend to strongly bond (chemisorbed) with low-k dielectric at pore inner surfaces and at the low-k/solid interface of porous low-k dielectrics. Therefore, water components at the surfaces, rather than the bulk, are likely more responsible for chemisorbed water related degradation of the interconnection layer. Although the method developed here was based on a model system study, we believe it should be applicable to a wide variety of low-k materials.
Collapse
Affiliation(s)
- Xiaoxian Zhang
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | | | | | | | | |
Collapse
|
48
|
Advanced experimental methods toward understanding biophysicochemical interactions of interfacial biomolecules by using sum frequency generation vibrational spectroscopy. Sci China Chem 2014. [DOI: 10.1007/s11426-014-5233-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|
49
|
Zhang C, Myers JN, Chen Z. Molecular behavior at buried epoxy/poly(ethylene terephthalate) interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12541-12550. [PMID: 25263030 DOI: 10.1021/la502239u] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Epoxies are widely used as main components in packaging underfills for microelectronics. Their strong adhesion to different substrate materials is an important factor for the functioning of electronic devices. Amines are commonly used cross-linking agents for epoxides. However, the molecular mechanisms of epoxide-amine mixture adhesion to substrate materials remain unclear. In this research we investigated the adhesion mechanism of epoxide-amine mixtures at poly(ethylene terephthalate) (PET) interfaces using attenuated total-internal reflection Fourier transform infrared (ATR-FTIR) spectroscopy and sum frequency generation (SFG) vibrational spectroscopy. Results show that both epoxide and amine could diffuse into the PET film. They could also dissolve or modify the PET film at the interphase region. In the process of epoxy curing on PET, epoxide molecules could cross-link with the modified PET film, providing strong adhesion. This hypothesis was further confirmed by adding reactive and nonreactive silanes to the epoxies and measuring the adhesion strengths of such mixtures to PET. The reactive silanes could cross-link with the system, showing good adhesion, while the nonreactive silane prevented sufficient cross-linking, showing poor adhesion. This research developed an in-depth insight for molecular behaviors at the epoxy/PET interface which helped clarify the related adhesion mechanism.
Collapse
Affiliation(s)
- Chi Zhang
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | | | | |
Collapse
|
50
|
Iqbal D, Rechmann J, Sarfraz A, Altin A, Genchev G, Erbe A. Synthesis of ultrathin poly(methyl methacrylate) model coatings bound via organosilanes to zinc and investigation of their delamination kinetics. ACS APPLIED MATERIALS & INTERFACES 2014; 6:18112-18121. [PMID: 25232896 DOI: 10.1021/am504992r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Polymer coatings are widely used to protect metals from corrosion. Coating adhesion to the base material is critical for good protection, but coatings may fail because of cathodic delamination. Most of the experimental studies on cathodic delamination use polymers to study the corrosion behavior under conditions where the interfacial chemistry at the metal(oxide)/polymer interface is not well-defined. Here, ultrathin linear and cross-linked poly(methyl methacrylate) [PMMA] coatings that are covalently bound to oxide-covered zinc via a silane linker have been prepared. For preparation, zinc was functionalized with vinyltrimethoxysilane (VTS), yielding a vinyl monomer-covered surface. These samples were subjected to thermally initiated free radical polymerization in the presence of methyl methacrylate (MMA) to yield surface-bound ultrathin PMMA films of 10-20 nm thickness, bound to the surface via Zn-O-Si bonds. A similar preparation was also carried out in the presence of different amounts of the cross-linkers ethylene glycol diacrylate and hexanediol diacrylate. Functionalized and polymer-coated zinc samples were characterized by infrared (IR) spectroscopy, secondary ion mass spectrometry (SIMS), ellipsometry, and X-ray photoelectron spectroscopy (XPS). Coating stability toward cathodic delamination has been evaluated by scanning Kelvin probe (SKP) experiments. In all cases, the covalently linked coatings show lower delamination rates of 0.02-0.2 mm h(-1) than coatings attached to the surface without covalent bonds (rates ∼10 mm h(-1)). Samples with a higher fraction of cross-linker delaminate slower, with rates down to 0.03-0.04 mm h(-1), compared to ∼0.3 mm h(-1) without cross-linker. Samples with longer hydrophobic alkyl chains also delaminate slower, with the lowest observed delamination rate of 0.028 mm h(-1) using hexanediol diacrylate. For the coatings studied here, delamination kinetics is not diffusion limited, but the rate is controlled by a chemical reaction. Several possibilities for the nature of this reaction are discussed; radical side reactions of the oxygen reduction are the most likely path of deadhesion.
Collapse
Affiliation(s)
- Danish Iqbal
- Max-Planck-Institut für Eisenforschung GmbH , Department of Interface Chemistry and Surface Engineering, Max-Planck-Str. 1, 40237 Düsseldorf, Germany
| | | | | | | | | | | |
Collapse
|