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Xu Z, Li G, Zhang Y, Wu Y, Lu X. Probing Interfacial Aging of Model Adhesion Joints under a Hygrothermal Environment at a Molecular Level. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:9280-9288. [PMID: 38619299 DOI: 10.1021/acs.langmuir.4c00696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Generally, for adhesive joints, the polar water molecules in humid environments can have a critical effect on the interfacial structures and structural evolution adjacent to the solid substrates. Regarding this, it is still a big challenge to detect and understand the interfacial hygrothermal aging process at the molecular level in real time and in situ. In this study, to trace the interfacial hygrothermal aging process of a classical epoxy formula containing diglycidyl ether of biphenyl A (DGEBA) and 2,2'-(ethylenedioxy) diethylamine (EDDA) with sapphire and fused silica in a typical hygrothermal environment (85 °C and 85% RH), sum frequency generation (SFG) vibrational spectroscopy was used to probe the molecular-level interfacial structural change over the time. The structural evolution dynamics at the buried epoxy/sapphire and epoxy/silica interfaces upon hygrothermal aging were revealed directly in situ. The interfacial delamination during hygrothermal aging was also elucidated from the molecular level. Upon hygrothermal aging, the interfacial CH signals, such as the ones from methyl, methylene, and phenyl groups, decreased significantly and the water OH signals increased substantially, indicating the water molecules had diffused into the interfaces and destroyed the original interactions between the epoxy formula and the substrates. Further analysis indicates that when the integrated signals in the CH range declined to their minimum and leveled off, the interfacial delamination happened. The tensile experiment proved the validity of these spectroscopic experimental results. Our study provides first-hand and molecular-level evidence on a direct correlation between the diffusion of the surrounding water molecules into the interface and the evolution/destruction of the interfacial structures during hygrothermal aging. More importantly, it is proved, SFG can be developed into a powerful tool to noninvasively reveal the local interfacial delamination in real time and in situ under extreme hygrothermal conditions, complemented by the mechanic test.
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Affiliation(s)
- Zhaohui Xu
- State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Gaoming Li
- Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621900, 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 Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
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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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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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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
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5
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Relaxation behavior of polymer thin films: Effects of free surface, buried interface, and geometrical confinement. Prog Polym Sci 2021. [DOI: 10.1016/j.progpolymsci.2021.101431] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Yamamoto S, Kuwahara R, Tanaka K. Dynamic behaviour of water molecules in heterogeneous free space formed in an epoxy resin. SOFT MATTER 2021; 17:6073-6080. [PMID: 34132297 DOI: 10.1039/d1sm00529d] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Although an epoxy resin is a stable material, it absorbs moisture over a long period of time, causing deterioration of its material properties. We here applied a full-atomistic molecular dynamics (MD) simulation to study where water molecules exist in an epoxy resin and how they dynamically behave. First, the curing reaction was simulated to obtain a network structure so that the time course of the density, and thereby the free space, in the resin were obtained. The results made it possible to discuss the formation and size distribution of the free spaces which were not connected to each other. Then, a few percent of water were inserted into the free space of the cured epoxy resin to examine the location and dynamics of their molecules. We found that several water molecules were clustered at a preferred site, where hydrogen bonds can be formed with hydroxy, ether and amino groups of the network, in the free space, and they heterogeneously moved from there to other sites.
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Affiliation(s)
- Satoru Yamamoto
- Centre for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan.
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Andre JS, Li B, Chen X, Paradkar R, Walther B, Feng C, Tucker C, Mohler C, Chen Z. Interfacial reaction of a maleic anhydride grafted polyolefin with ethylene vinyl alcohol copolymer at the buried solid/solid interface. POLYMER 2021. [DOI: 10.1016/j.polymer.2020.123141] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Vuković F, Walsh TR. Moisture Ingress at the Molecular Scale in Hygrothermal Aging of Fiber-Epoxy Interfaces. ACS APPLIED MATERIALS & INTERFACES 2020; 12:55278-55289. [PMID: 33226762 DOI: 10.1021/acsami.0c17027] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Almost all applications of carbon fiber reinforced composites are susceptible to water aging, either via ambient humidity or through direct exposure to liquid water environments. Although the impacts of water aging in composites can be readily quantified via experimental efforts, details regarding the mechanisms of moisture ingress and aging, particularly at the incipient stages of aging under hygrothermal conditions, have proven challenging to resolve using experimental techniques alone. A deeper understanding of the factors that drive incipient moisture ingress during aging is required for more targeted approaches to combat water aging. Here, molecular dynamics simulations of a novel epoxy/carbon fiber interface exposed to liquid water under hygrothermal conditions are used to elucidate molecular details of the moisture ingress mechanisms at the incipient stages of the aging process. Remarkably, the simulations show that the fiber-matrix interface is not vulnerable to a moisture-wicking type of incipient water ingress and does not readily flood in these early stages of water aging. Instead, water is preferentially absorbed via the matrix-water interface, an ingress pathway that is facilitated by the dynamic mobility of polymer chains at this interface. These chains present electronegative sites that can capture water molecules and provide a conduit to transiently exposed pores and channels on the polymer surface, which creates a presoaked staging reservoir for subsequent deeper ingress into the composite. Characterization of the absorbed water is according to hydrogen bonding to the matrix, and the distributions and transport behavior of these waters are consistent with experimental observations. This work introduces new insights regarding the molecular-level details of moisture ingress and spatial distribution of water in these materials during hygrothermal aging, informing future design directions for extending both the service life and shelf life of next-generation composites.
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Affiliation(s)
- Filip Vuković
- Institute for Frontier Materials, Deakin University, Geelong, VIC 3216, Australia
| | - Tiffany R Walsh
- Institute for Frontier Materials, Deakin University, Geelong, VIC 3216, Australia
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Zhang L, Tan J, Pei Q, Ye S. Film thickness and surface plasmon tune the contribution of SFG signals from buried interface and air surface. CHINESE J CHEM PHYS 2020. [DOI: 10.1063/1674-0068/cjcp2006113] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Liang Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Junjun Tan
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Quanbing Pei
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information Quantum Physics, University of Science and Technology of China, Hefei 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 230026, China
- Synergetic Innovation Center of Quantum Information Quantum Physics, University of Science and Technology of China, Hefei 230026, China
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Vergara JH, Tian Y, La Scala JJ, Sadler JM, Palmese GR. Synthesis and characterization of fatty acid modified amines with improved water barrier properties. Eur Polym J 2017. [DOI: 10.1016/j.eurpolymj.2017.09.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Vergara J, La Scala J, Henry C, Sadler J, Yadav S, Palmese G. The effect of pendant alkyl chain length on the barrier properties of epoxy/amine crosslinked networks. POLYMER 2017. [DOI: 10.1016/j.polymer.2017.10.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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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.
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Affiliation(s)
- Chi Zhang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
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Ulrich NW, Andre J, Williamson J, Lee KW, Chen Z. Plasma treatment effect on polymer buried interfacial structure and property. Phys Chem Chem Phys 2017; 19:12144-12155. [DOI: 10.1039/c7cp00567a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Adhesion is important in many industrial applications including those in the microelectronics industry.
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Affiliation(s)
- Nathan W. Ulrich
- Department of Chemistry
- University of Michigan
- 930 North University Avenue
- Ann Arbor
- USA
| | - John Andre
- Department of Chemistry
- Humboldt State University
- Arcata
- USA
| | | | - Kang-Wook Lee
- IBM Thomas J. Watson Research Center
- Yorktown Heights
- USA
| | - Zhan Chen
- Department of Chemistry
- University of Michigan
- 930 North University Avenue
- Ann Arbor
- USA
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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
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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]
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Ulrich NW, Myers JN, Chen Z. Characterization of polymer/epoxy buried interfaces with silane adhesion promoters before and after hygrothermal aging for the elucidation of molecular level details relevant to adhesion. RSC Adv 2015. [DOI: 10.1039/c5ra24332g] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Buried interfacial structures containing epoxy underfills are incredibly important in the microelectronics industry and their structures determine the interfacial adhesion properties and ultimately their lifetime.
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Affiliation(s)
| | - John N. Myers
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
| | - Zhan Chen
- Department of Chemistry
- University of Michigan
- Ann Arbor
- USA
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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.
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Affiliation(s)
- Xiaoxian Zhang
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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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.
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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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