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Wu Y, Lin T, Santos E, Ahn D, Marson R, Sarker P, Chen X, Gubbels F, Shephard NE, Mohler C, Wei T, Kuo TC, Chen Z. Molecular behavior of silicone adhesive at buried polymer interface studied by molecular dynamics simulation and sum frequency generation vibrational spectroscopy. SOFT MATTER 2024; 20:4765-4775. [PMID: 38841820 DOI: 10.1039/d4sm00407h] [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
Silicones have excellent material properties and are used extensively in many applications, ranging from adhesives and lubricants to electrical insulation. To ensure strong adhesion of silicone adhesives to a wide variety of substrates, silane-based adhesion promotors are typically blended into the silicone adhesive formulation. However, little is known at the molecular level about the true silane adhesion promotion mechanism, which limits the ability to develop even more effective adhesion promoters. To understand the adhesion promotion mechanism of silane molecules at the molecular level, this study has used sum frequency generation vibrational spectroscopy (SFG) to determine the behavior of (3-glycidoxypropyl)trimethoxy silane (γ-GPS) at the buried interface between poly(ethylene terephthalate) (PET) and a bulk silicone adhesive. To complement and extend the SFG results, atomistic molecular dynamics (MD) simulations were applied to investigate molecular behavior and interfacial interaction of γ-GPS at the silicone/PET interface. Free energy computations were used to study the γ-GPS interaction in the sample system and determine the γ-GPS interfacial segregation mechanism. Both experiments and simulations consistently show that γ-GPS molecules prefer to segregate at the interface between PET and PDMS. The methoxy groups on γ-GPS molecules orient toward the PDMS polymer phase. The consistent picture of interfacial structure emerging from both simulation and experiment provides enhanced insight on how γ-GPS behaves in the silicone - PET system and illustrates why γ-GPS could improve the adhesion of silicone adhesive, leading to further understanding of silicone adhesion mechanisms useful in the design of silicone adhesives with improved performance.
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Affiliation(s)
- Yuchen Wu
- Department of Chemistry, University of Michigan, MI 48109, USA.
- Department of Macromolecular Science and Engineering, University of Michigan, MI 48109, USA
| | - Ting Lin
- Department of Chemistry, University of Michigan, MI 48109, USA.
- Department of Macromolecular Science and Engineering, University of Michigan, MI 48109, USA
| | | | - Dongchan Ahn
- The Dow Chemical Company, Midland, MI 48674, USA
| | - Ryan Marson
- The Dow Chemical Company, Midland, MI 48674, USA
| | - Pranab Sarker
- Department of Biomedical Engineering, University of South Carolina, Columbia, SC 29208, USA.
- Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, USA
| | - Xiaoyun Chen
- The Dow Chemical Company, Midland, MI 48674, USA
| | | | | | - Carol Mohler
- The Dow Chemical Company, Midland, MI 48674, USA
| | - Tao Wei
- Department of Biomedical Engineering, University of South Carolina, Columbia, SC 29208, USA.
- Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, USA
| | - Tzu-Chi Kuo
- The Dow Chemical Company, Midland, MI 48674, USA
| | - Zhan Chen
- Department of Chemistry, University of Michigan, MI 48109, USA.
- Department of Macromolecular Science and Engineering, University of Michigan, MI 48109, USA
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Kawaguchi D, Sasahara K, Inutsuka M, Abe T, Yamamoto S, Tanaka K. Absolute local conformation of poly(methyl methacrylate) chains adsorbed on a quartz surface. J Chem Phys 2023; 159:244902. [PMID: 38146829 DOI: 10.1063/5.0184315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 11/30/2023] [Indexed: 12/27/2023] Open
Abstract
Polymer chains at a buried interface with an inorganic solid play a critical role in the performance of polymer nanocomposites and adhesives. Sum frequency generation (SFG) vibrational spectroscopy with a sub-nanometer depth resolution provides valuable information regarding the orientation angle of functional groups at interfaces. However, in the case of conventional SFG, since the signal intensity is proportional to the square of the second-order nonlinear optical susceptibility and thereby loses phase information, it cannot be unambiguously determined whether the functional groups face upward or downward. This problem can be solved by phase-sensitive SFG (ps-SFG). We here applied ps-SFG to poly(methyl methacrylate) (PMMA) chains in direct contact with a quartz surface, shedding light on the local conformation of chains adsorbed onto the solid surface. The measurements made it possible to determine the absolute orientation of the ester methyl groups of PMMA, which were oriented toward the quartz interface. Combining ps-SFG with all-atomistic molecular dynamics simulation, the distribution of the local conformation and the driving force are also discussed.
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Affiliation(s)
- Daisuke Kawaguchi
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Kazuki Sasahara
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | - Manabu Inutsuka
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | - Tatsuki Abe
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
| | - Satoru Yamamoto
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Keiji Tanaka
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
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de Lima BM, Hayes PL, Wood-Adams PM. Lamellar orientation at the surface of isotactic polystyrene thin films analyzed by sum frequency generation spectroscopy. Anal Chim Acta 2023; 1248:340904. [PMID: 36813456 DOI: 10.1016/j.aca.2023.340904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/12/2023] [Accepted: 01/27/2023] [Indexed: 01/30/2023]
Abstract
Analyzing the orientation of polymeric crystalline lamella at the surface of thin films can be challenging. Even though atomic force microscopy (AFM) is often sufficient for this analysis, there are cases when imaging is not sufficient to confidently determine lamellar orientation. Here, we used sum frequency generation (SFG) spectroscopy to analyze the lamellar orientation at the surface of semi-crystalline isotactic polystyrene (iPS) thin films. The SFG orientation analysis indicated that the iPS chains are oriented perpendicular to the substrate (flat-on lamellar orientation), which was confirmed by AFM. By analyzing the evolution of the SFG spectral features with the progress of crystallization, we demonstrated that the ratios of the SFG intensities of the phenyl ring resonances are a good indication of the surface crystallinity. Furthermore, we explored the challenges associated with SFG measurements of heterogeneous surfaces, which is commonly present in many semi-crystalline polymeric films. To the best of our knowledge, this is the first time that the surface lamellar orientation of semi-crystalline polymeric thin films was determined by SFG. Also, this work pioneers in reporting the surface conformation of semi-crystalline and amorphous iPS thin films by SFG and in linking the SFG intensity ratios to the progress of the crystallization and the surface crystallinity. This study demonstrates the potential applicability of SFG spectroscopy in the conformational analysis of polymeric crystalline structures at interfaces and opens the way to the investigation of more complex polymeric structures and crystalline arrangements, especially for the case of buried interfaces, where AFM imaging is not an option.
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Affiliation(s)
- Bianca M de Lima
- Department of Chemical and Materials Engineering, Concordia University, 1435 Rue Guy, S-GM 900-13, Montréal, Québec, H3H 2L5, Canada
| | - Patrick L Hayes
- Department of Chemistry, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, Québe, H2V 0B3, Canada.
| | - Paula M Wood-Adams
- Department of Chemical and Materials Engineering, Concordia University, 1435 Rue Guy, S-GM 900-13, Montréal, Québec, H3H 2L5, Canada.
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Li B, Ma Y, Han X, Hu P, Lu X. Enhanced Sum Frequency Generation for Monolayers on Au Relative to Silica: Local Field Factors and SPR Effect. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:659-667. [PMID: 36580605 DOI: 10.1021/acs.langmuir.2c03016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Using metals as signal magnified substrates, surface plasmon-enhanced sum frequency generation (SFG) vibrational spectroscopy is a promising technique to probe weak molecular-level signals at surfaces and interfaces. In this study, the vibrational signals of the n-alkane monolayer on the gold (Au) and silica substrates are investigated using the broadband femtosecond SFG. The enhancement factors are discovered to be up to ∼1076 and ∼31 for the methyl symmetric and asymmetric stretching (ss and as) modes of the monolayer, respectively. By systematically analyzing the second-order nonlinear susceptibility tensor components (χijks), the Fresnel coefficients (Fijks), and the surface plasmon resonance (SPR) effect, we find that the interplay between Fijk and χijk terms and the SPR effect dominate the SFG signal enhancement. Our study reveals that the relative contributions of different influencing factors (i.e., Fresnel coefficients and SPR) to the SFG signal enhancement provide an approach to interpreting enhanced SFG vibrational signals detected from probe molecules on distinct substrates and may finally guide the design of the experimental methodology to improve the detection sensitivity and signal-to-noise ratio.
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Affiliation(s)
- Bolin Li
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory (HMFL), Hefei Institutes of Physical Science (HFIPS), Chinese Academy of Sciences, Hefei, Anhui230031, P. R. China
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing210096, China
| | - Yonghao Ma
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing210096, China
| | - Xiaofeng Han
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing210096, China
| | - Pengcheng Hu
- School of Medical Imaging, Xuzhou Medical College, Xuzhou, Jiangsu221004, China
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing210096, China
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Dialkyl carbonates enforce energy storage as new dielectric liquids. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Local conformations and heterogeneities in structures and dynamics of isotactic polypropylene adsorbed onto carbon fiber. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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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.
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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
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Sum frequency generation imaging for semi-crystalline polymers. Polym J 2022. [DOI: 10.1038/s41428-021-00613-9] [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]
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