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Kumar N, Premadasa UI, Dong D, Roy S, Ma YZ, Doughty B, Bryantsev VS. Adsorption, Orientation, and Speciation of Amino Acids at Air-Aqueous Interfaces for the Direct Air Capture of CO 2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:14311-14320. [PMID: 38958522 DOI: 10.1021/acs.langmuir.4c00907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Amino acids make up a promising family of molecules capable of direct air capture (DAC) of CO2 from the atmosphere. Under alkaline conditions, CO2 reacts with the anionic form of an amino acid to produce carbamates and deactivated zwitterionic amino acids. The presence of the various species of amino acids and reactive intermediates can have a significant effect on DAC chemistry, the role of which is poorly understood. In this study, all-atom molecular dynamics (MD) based computational simulations and vibrational sum frequency generation (vSFG) spectroscopy studies were conducted to understand the role of competitive interactions at the air-aqueous interface in the context of DAC. We find that the presence of potassium bicarbonate ions, in combination with the anionic and zwitterionic forms of amino acids, induces concentration and charge gradients at the interface, generating a layered molecular arrangement that changes under pre- and post-DAC conditions. In parallel, an enhancement in the surface activity of both anionic and zwitterionic forms of amino acids is observed, which is attributed to enhanced interfacial stability and favorable intermolecular interactions between the adsorbed amino acids in their anionic and zwitterionic forms. The collective influence of these competitive interactions, along with the resulting interfacial heterogeneity, may in turn affect subsequent capture reactions and associated rates. These effects underscore the need to consider dynamic changes in interfacial chemical makeup to enhance DAC efficiency and to develop successful negative emission and storage technologies.
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Affiliation(s)
- Nitesh Kumar
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Uvinduni I Premadasa
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Dengpan Dong
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Santanu Roy
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Ying-Zhong Ma
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Benjamin Doughty
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Vyacheslav S Bryantsev
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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2
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Lai J, Zhu R, Tan J, Yang Z, Ye S. Stacking Arrangement and Orientation of Aromatic Cations Tune Bandgap and Charge Transport of 2D Organic-Inorganic Hybrid Perovskites. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2303449. [PMID: 37495901 DOI: 10.1002/smll.202303449] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/10/2023] [Indexed: 07/28/2023]
Abstract
Chemical modifications on aromatic spacers of 2D perovskites have been demonstrated to be an effective strategy to simultaneously improve optoelectronic properties and stability. However, its underlying mechanism is poorly understood. By using 2D phenyl-based perovskites ([C6 H5 (CH2 )m NH3 ]2 PbI4 ) as models, the authors have revealed how the chemical nature of aromatic cations tunes the bandgap and charge transport of 2D perovskites by utilizing sum-frequency generation vibrational spectroscopy to determine the stacking arrangement and orientation of aromatic cations. It is found that the antiparallel slip-stack arrangement of phenyl rings between adjacent layers induces an indirect band gap, resulting in anomalous carrier dynamics. Incorporation of the CH2 moiety causes stacking rearrangement of the phenyl ring and thus promotes an indirect to direct bandgap transition. In direct-bandgap perovskites, higher carrier mobility correlates with a larger orientation angle of the phenyl ring. Further optimizing the orientation angle by introducing a para-substituted element in a phenyl ring, higher carrier mobility is obtained. This work highlights the importance of leveraging stacking arrangement and orientation of the aromatic cations to tune the photophysical properties, which opens up an avenue for advancing high-performance 2D perovskites optoelectronics via molecular engineering.
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Affiliation(s)
- Jing Lai
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Renlong Zhu
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Junjun Tan
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui, 230088, China
| | - Zhe Yang
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Shuji Ye
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui, 230088, China
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3
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Xu Z, Zhang Y, Wu Y, Lu X. Spectroscopically Detecting Molecular-Level Bonding Formation between an Epoxy Formula and Steel. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:13261-13271. [PMID: 36254887 DOI: 10.1021/acs.langmuir.2c02325] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The formation of the interfacial adhesion between an epoxy adhesive and a substrate was normally accompanied by the epoxy curing process on the substrate. Although the debate on the formation mechanism of the interfacial adhesion is still ongoing, this issue can causally be resolved by studying the interfacial structural formation between the epoxy adhesive and the substrate. Herein, to reveal the interfacial structural formation of a representative formula composed of epoxy (digylcidyl ether of biphenyl A, DGEBA) and amine hardener (2,2'-(ethylenedioxy) diethylamine, EDDA) with the steel substrate upon curing and postcuring treatments, sum-frequency generation (SFG) vibrational spectroscopy with a sandwiched transparent window/epoxy adhesive/steel setup was applied to detect and track the buried molecular-level structures at the epoxy adhesive/steel interface. An X-ray photoelectron spectroscopic (XPS) experiment was performed to probe the intentionally exposed interface to disclose the occurring interfacial chemical reaction. The reaction between the epoxy groups and the steel-surface OH groups and the molecular reconstruction of interfacial epoxy methyl groups upon curing and postcuring steps were confirmed. The latter also indirectly indicated the formation of the additional hydrogen bonding and the former bonding reaction at the interface. The above two spectroscopic experimental results matched up with the further examination of the adhesion strength. Therefore, this work elucidates the formation of the interfacial bonding between the epoxy formula and the steel substrate upon curing and postcuring treatments at the molecular level, thus providing an in-depth insight into the origin of the interfacial adhesion.
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Affiliation(s)
- Zhaohui Xu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing210096, China
| | - Yinyu Zhang
- Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang621900, China
| | - Yeping Wu
- Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang621900, China
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing210096, China
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4
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Xu Z, Zhang Y, Wu Y, Lu X. Molecular-Level Correlation between Spectral Evidence and Interfacial Bonding Formation for Epoxy Adhesives on Solid Substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5847-5856. [PMID: 35441517 DOI: 10.1021/acs.langmuir.2c00470] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Interfacial bonding strength of an epoxy-based adhesive depends on the interfacial interaction between the adhesive and the substrate. Normally, the curing process at the interface accompanied by the interfacial bonding formation is different from that in the bulk, and it is still a big challenge to probe the interfacial bonding formation at a molecular level. In this study, to trace the interfacial structural evolution of a representative formula of epoxy (digylcidyl ether of biphenyl A, DGEBA) and amine hardener [1,2-bis(2-aminoethoxy)ethane, EDDA] with the sapphire and silica substrates upon curing and post-curing steps, sum frequency generation (SFG) vibrational spectroscopy is employed to detect the molecular-level interfacial structural information. For the sapphire substrate, upon curing, backbone methylene (CH2) stretching signals decrease, indicating the formation of a rigid chain network structure and thus losing the local methylene order, while vibrational signals of the sapphire surface hydroxyl (OH) groups (including hydrogen-bonded and unbonded) increase significantly, indicating the formation of a strong hydrogen-bonding and polar interaction between the epoxy adhesive and the sapphire surface. Upon post-curing, increased backbone CH2 signals and decreased sapphire OH signals suggest interfacial chemical bonding formation due to the reaction between the epoxy rings and the sapphire surface OH groups. Orientation analysis confirms the enhanced ordering of the sapphire surface OH groups upon curing and post-curing, in comparison to the uncured epoxy formula. As for the fused silica, weak vibrational signals of the methylene (CH2) and methyl (CH3) groups are observed before curing, while both of them increase slightly for the cured and post-cured epoxy formulae, suggesting relatively less hydrophilic nature of the silica surface compared to that of the sapphire surface, also evidenced by the very weak OH signals upon curing and post-curing. Further measurement on the adhesion strength matches up with the above spectroscopic experimental results, substantiating the correlation between the macroscopic bonding strength of the epoxy adhesive and the microscopic molecular-level structure.
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Affiliation(s)
- Zhaohui Xu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Yinyu Zhang
- Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621900, China
| | - Yeping Wu
- Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621900, China
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
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5
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Luo Y, Pang AP, Zhu P, Wang D, Lu X. Demonstrating the Interfacial Polymer Thermal Transition from Coil-to-Globule to Coil-to-Stretch under Shear Flow Using SFG and MD Simulation. J Phys Chem Lett 2022; 13:1617-1627. [PMID: 35142518 DOI: 10.1021/acs.jpclett.1c03866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Revealing interfacial shear-induced structural responsiveness has long been an important topic in that most fluids in nature and human life are in motion and cause interesting boundary phenomena. It is amazing how the polymer chain conformation or local structural features at a boundary change under the effective shear condition. In this study, microfluidic-assisted sum frequency generation (SFG) vibrational spectroscopy and all-atom molecular dynamics (MD) simulation are combined to reveal that the shear flow can effectively block the so-called thermal coil-to-globule transition of the poly(N-isopropylacrylamide) (PNIPAM) brushes on the solid substrate, and the normal coil-to-globule transition transfers to a coil-to-stretch one under shear flow with increasing ambient temperature. Such findings are attributed to the balance between the shear flow and the molecular interaction with respect to the polymer chains and adjacent water molecules, thus demonstrating the significant effect of the shear flow on the structural and dynamic behaviors of the polymer chains at the boundaries from the molecular level.
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Affiliation(s)
- Yongsheng Luo
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
| | - Ai-Ping Pang
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
| | - Peizhi Zhu
- College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225009, Jiangsu Province, P. R. China
| | - Dayang Wang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, Jilin Province, P. R. China
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
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6
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Chaudhary S, Kaur H, Kaur H, Rana B, Tomar D, Jena KC. Probing the Bovine Hemoglobin Adsorption Process and its Influence on Interfacial Water Structure at the Air-Water Interface. APPLIED SPECTROSCOPY 2021; 75:1497-1509. [PMID: 34346774 DOI: 10.1177/00037028211035157] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
*These authors contributed equally to this work.The molecular-level insight of protein adsorption and its kinetics at interfaces is crucial because of its multifold role in diverse fundamental biological processes and applications. In the present study, the sum frequency generation (SFG) vibrational spectroscopy has been employed to demonstrate the adsorption process of bovine hemoglobin (BHb) protein molecules at the air-water interface at interfacial isoelectric point of the protein. It has been observed that surface coverage of BHb molecules significantly influences the arrangement of the protein molecules at the interface. The time-dependent SFG studies at two different frequencies in the fingerprint region elucidate the kinetics of protein denaturation process and its influence on the hydrogen-bonding network of interfacial water molecules at the air-water interface. The initial growth kinetics suggests the synchronized behavior of protein adsorption process with the structural changes in the interfacial water molecules. Interestingly, both the events carry similar characteristic time constants. However, the conformational changes in the protein structure due to the denaturation process stay for a long time, whereas the changes in water structure reconcile quickly. It is revealed that the protein denaturation process is followed by the advent of strongly hydrogen-bonded water molecules at the interface. In addition, we have also carried out the surface tension kinetics measurements to complement the findings of our SFG spectroscopic results.
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Affiliation(s)
- Shilpi Chaudhary
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
- Department of Applied Sciences, Punjab Engineering College (Deemed to be University), Chandigarh, India
| | - Harsharan Kaur
- Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar, India
| | - Harpreet Kaur
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
| | - Bhawna Rana
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
| | - Deepak Tomar
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
| | - Kailash C Jena
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar, India
- Department of Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar, India
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7
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Riaz S, Friedrichs G. Vibrational sum-frequency generation study of molecular structure, sterical constraints and nonlinear optical switching contrast of mixed alkyl-azobenzene self-assembled monolayers. Z PHYS CHEM 2020. [DOI: 10.1515/zpch-2020-1655] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Abstract
Self-assembled monolayers (SAMs) of azobenzene (AB) functionalized alkyl thiols on gold diluted with simple alkyl thiols provide a straightforward way to photochromic surfaces with high and tunable photoswitching efficiency. Trans-cis isomerization of the AB molecule changes the physical properties of the surface, including the nonlinear optical (NLO) response. Vibrational sum-frequency generation (VSFG) spectroscopy as a nonlinear type of laser spectroscopy offers surface- and orientation-sensitive insight into the molecular structure of mixed SAMs. In this study, VSFG as well as ultraviolet-visible (UV/Vis) spectroscopy has been employed to investigate the morphology, molecular structure, and NLO response of mixed SAMs with systematically varied surface composition. Methylazobenzene (MeAB) has been used as the molecular switch with the methyl substituent serving as orientational VSFG marker. Both short-chain and long-chain alkyl thiol co-ligands have been used to gain insight into the interplay between SAM structure and sterical constraints that are known to limit the free switching volume. Underlining the dominating role of sterical effects for controlling photochromic properties, a strong inhibition of the photoswitching efficiency and NLO response has been observed for the SAMs with an alkyl thiol co-ligand long enough to spatially extend into the layer of the MeAB chromophore. Overall, with <12% signal change, the relative NLO switching contrasts remained low in all cases. VSFG spectral trends clearly revealed that the presumably higher photoswitching efficiency upon dilution with the co-ligand is counteracted by a loss of structural order of the chromophore.
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Affiliation(s)
- Saira Riaz
- Islamabad College for Girls , F-6/2 , Islamabad, 44000 , Pakistan
| | - Gernot Friedrichs
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel , Max-Eyth-Str. 1, 24118 , Kiel , Germany
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8
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Li X, Lu X. Evolution of Irreversibly Adsorbed Layer Promotes Dewetting of Polystyrene Film on Sapphire. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b01141] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Xu Li
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
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9
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Ge A, Matsusaki M, Qiao L, Akashi M, Ye S. Salt Effects on Surface Structures of Polyelectrolyte Multilayers (PEMs) Investigated by Vibrational Sum Frequency Generation (SFG) Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:3803-3810. [PMID: 27045932 DOI: 10.1021/acs.langmuir.5b04765] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Sum frequency generation (SFG) vibrational spectroscopy was employed to investigate the surface structures of polyelectrolyte multilayers (PEMs) constructed by sequentially alternating adsorption of poly(diallyldimethylammonium chloride) (PDDA) and poly(styrenesulfonate) (PSS). It was found that the surface structures and surface charge density of the as-deposited PEMs of PDDA/PSS significantly depend on the concentration of sodium chloride (NaCl) present in the polyelectrolyte solutions. Furthermore, it was found that the surface structure of the as-deposited PEMs is in a metastable state and will reach the equilibrium state by diffusion of the polyelectrolyte chain after an aging process, resulting in a polyelectrolyte mixture on the PEM surfaces.
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Affiliation(s)
- Aimin Ge
- Institute for Catalysis, Hokkaido University , Sapporo 001-0021, Japan
| | - Michiya Matsusaki
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University , Osaka 565-0871, Japan
| | - Lin Qiao
- Institute for Catalysis, Hokkaido University , Sapporo 001-0021, Japan
| | - Mitsuru Akashi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University , Osaka 565-0871, Japan
| | - Shen Ye
- Institute for Catalysis, Hokkaido University , Sapporo 001-0021, Japan
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10
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Li X, Li B, Zhang X, Li C, Guo Z, Zhou D, Lu X. Detecting Surface Hydration of Poly(2-hydroxyethyl methacrylate) in Solution in situ. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00389] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Xu Li
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province P. R. China
| | - Bolin Li
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province P. R. China
| | - Xiaodong Zhang
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province P. R. China
| | - Chengcheng Li
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province P. R. China
| | - Zhirui Guo
- Department
of Geriatrics, Second Affiliated Hospital of Nanjing Medical University, Nanjing 210029, P. R. China
| | - Dongshan Zhou
- Department
of Polymer Science and Engineering, School of Chemistry and Chemical
Engineering, State Key Laboratory of Coordination Chemistry, Nanjing
National Laboratory of Microstructure, Nanjing University, Nanjing 210093, P. R. China
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province P. R. China
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11
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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.
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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
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12
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Leng C, Liu Y, Jenkins C, Meredith H, Wilker JJ, Chen Z. Interfacial structure of a DOPA-inspired adhesive polymer studied by sum frequency generation vibrational spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:6659-64. [PMID: 23663073 DOI: 10.1021/la4008729] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Marine mussels deposit adhesive proteins containing 3,4-dihydroxyphenylalanine (DOPA) to attach themselves to different surfaces. Isolating such proteins from biological sources for adhesion purposes tends to be challenging. Recently, a simplified synthetic adhesive polymer, poly[(3,4-dihydroxystyrene)-co-styrene] (PDHSS), was developed to mimic DOPA-containing proteins. The pendant catechol group in this polymer provides cross-linking and adhesion much like mussel proteins do. In this work, sum frequency generation (SFG) vibrational spectroscopy was applied to reveal the structures of this DOPA-inspired polymer at air, water, and polymer interfaces. SFG spectroscopy results showed that when underwater, the catechol rings and the quinone rings were ordered, ready to adhere to surfaces. At the hydrophobic polystyrene interface, benzene π-π stacking is likely the adhesive force, whereas at the hydrophilic poly(allylamine) interface, primary amines may form hydrogen bonds with catechol or react with quinones for adhesion.
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Affiliation(s)
- Chuan Leng
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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13
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Zhang C, Myers J, Chen Z. Elucidation of molecular structures at buried polymer interfaces and biological interfaces using sum frequency generation vibrational spectroscopy. SOFT MATTER 2013; 9:4738-4761. [PMID: 23710244 PMCID: PMC3661304 DOI: 10.1039/c3sm27710k] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Sum frequency generation (SFG) vibrational spectroscopy has been developed into an important technique to study surfaces and interfaces. It can probe buried interfaces in situ and provide molecular level structural information such as the presence of various chemical moieties, quantitative molecular functional group orientation, and time dependent kinetics or dynamics at such interfaces. This paper focuses on these three most important advantages of SFG and reviews some of the recent progress in SFG studies on interfaces related to polymer materials and biomolecules. The results discussed here demonstrate that SFG can provide important molecular structural information of buried interfaces in situ and in real time, which is difficult to obtain by other surface sensitive analytical techniques.
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Affiliation(s)
- Chi Zhang
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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14
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Lu X, Xue G, Wang X, Han J, Han X, Hankett J, Li D, Chen Z. Directly Probing Molecular Ordering at the Buried Polymer/Metal Interface 2: Using P-Polarized Input Beams. Macromolecules 2012. [DOI: 10.1021/ma301088g] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Xiaolin Lu
- Department of Chemistry, Key
Laboratory of Advanced Textile Materials and Manufacturing Technology
of Education Ministry, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Gi Xue
- Department of Polymer Science, Nanjing University, Nanjing, 210093, China
| | - Xinping Wang
- Department of Chemistry, Key
Laboratory of Advanced Textile Materials and Manufacturing Technology
of Education Ministry, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Jianglong Han
- Department of Polymer Science, Nanjing University, Nanjing, 210093, China
| | - Xiaofeng Han
- Department of Chemistry, University of Michigan, 930 North University Avenue,
Ann Arbor, Michigan 48109, United States
| | - Jeanne Hankett
- Department of Chemistry, University of Michigan, 930 North University Avenue,
Ann Arbor, Michigan 48109, United States
| | - Dawei Li
- Department of Polymer Science, Nanjing University, Nanjing, 210093, China
| | - Zhan Chen
- Department of Chemistry, University of Michigan, 930 North University Avenue,
Ann Arbor, Michigan 48109, United States
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15
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Hankett JM, Zhang C, Chen Z. Sum frequency generation and coherent anti-Stokes Raman spectroscopic studies on plasma-treated plasticized polyvinyl chloride films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:4654-4662. [PMID: 22309397 DOI: 10.1021/la2045527] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Polyvinyl chloride (PVC) is a widely used polymer to which various phthalates are extensively applied as plasticizers. PVC materials are often treated with plasma to vary the hydrophobicity or for cleaning purposes, but little is known of the nature of the surface molecular structures after treatment. This research characterizes molecular surface structures of PVC and bis-2-ethylhexyl phthalate (DEHP)-plasticized PVC films in air before annealing, after annealing, and after exposure to air-generated glow discharge plasma using sum frequency generation (SFG) vibrational spectroscopy. In addition, we compare the vibrational molecular signatures on the surfaces of PVC with DEHP (at a variety of percent loadings) to those of the bulk detected using coherent anti-Stokes Raman scattering (CARS). X-ray photoelectron spectroscopy (XPS) and contact angle measurements have been used to analyze PVC surfaces to supplement SFG data. Our results indicate that DEHP was found on the surfaces of PVC films even at low weight percentages (5 wt %) and that DEHP segregates on surfaces after annealing. The treatment of these films with glow discharge plasma resulted in surface-sensitive reactions involving the removal of chlorine atoms, the addition of oxygen atoms, and C-H bond rearrangement. CARS data demonstrate that the bulk of our films remained undisturbed during the plasma treatment. For the first time, we probed the molecular structure of the surface and the bulk of a PVC material using combined SFG and CARS studies on the same sample in exactly the same environment. In addition, the methodology used in this research can be applied to characterize various plasticizers in a wide variety of polymer systems to understand their surface and bulk structures before and after systematic applications of heat, plasma, or other treatments.
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Affiliation(s)
- Jeanne M Hankett
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Vázquez AV, Holden B, Kristalyn C, Fuller M, Wilkerson B, Chen Z. Surface and buried interfacial structures of epoxy resins used as underfills studied by sum frequency generation vibrational spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2011; 3:1640-1651. [PMID: 21504140 DOI: 10.1021/am2001899] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Flip chip technology has greatly improved the performance of semiconductor devices, but relies heavily on the performance of epoxy underfill adhesives. Because epoxy underfills are cured in situ in flip chip semiconductor devices, understanding their surface and interfacial structures is critical for understanding their adhesion to various substrates. Here, sum frequency generation (SFG) vibrational spectroscopy was used to study surface and buried interfacial structures of two model epoxy resins used as underfills in flip chip devices, bisphenol A digylcidyl ether (BADGE) and 1,4-butanediol diglycidyl ether (BDDGE). The surface structures of these epoxies were compared before and after cure, and the orientations of their surface functional groups were deduced to understand how surface structural changes during cure may affect adhesion properties. Further, the effect of moisture exposure, a known cause of adhesion failure, on surface structures was studied. It was found that the BADGE surface significantly restructured upon moisture exposure while the BDDGE surface did not, showing that BADGE adhesives may be more prone to moisture-induced delamination. Lastly, although surface structure can give some insight into adhesion, buried interfacial structures more directly correspond to adhesion properties of polymers. SFG was used to study buried interfaces between deuterated polystyrene (d-PS) and the epoxies before and after moisture exposure. It was shown that moisture exposure acted to disorder the buried interfaces, most likely due to swelling. These results correlated with lap shear adhesion testing showing a decrease in adhesion strength after moisture exposure. The presented work showed that surface and interfacial structures can be correlated to adhesive strength and may be helpful in understanding and designing optimized epoxy underfill adhesives.
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Affiliation(s)
- Anne V Vázquez
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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