TY - JOUR
T1 - Entropy-driven segregation in epoxy-amine systems at a copper interface
AU - Yamamoto, Satoru
AU - Tanaka, Keiji
N1 - Funding Information:
The authors thank R. Kuwahara (Dassault Systèmes K. K.) for helpful comments and discussions. This research was supported by JST-Mirai Program (JPMJMI18A2).
Publisher Copyright:
© The Royal Society of Chemistry 2020.
PY - 2021/2/7
Y1 - 2021/2/7
N2 - The composition of an epoxy resin at the interface with the adherend is usually different from that in the bulk due to the enrichment of a specific constituent, a characteristic called interfacial segregation. For better adhesion, it should be precisely understood how epoxy and amine molecules exist on the adherend surface and react with each other to form a three-dimensional network. In this study, the entropic factor of the segregation in a mixture of epoxy and amine at the copper interface before and after the curing reaction is discussed on the basis of a full-atomistic molecular dynamics (MD) simulation. Smaller molecules were preferentially segregated at the interface regardless of the epoxy and amine, and this segregation remained after the curing process. No segregation occurred at the interface for a combination composed of epoxy and amine molecules with a similar size. These findings make it clear that the size disparity between constituents affects the interfacial segregationviathe packing and/or translational entropy. The curing reaction was slower near the interface than in the bulk, and a large amount of unreacted molecules remained there. Finally, the effect of molecular shape was also examined. Linear molecules were more likely to segregate than round-shaped ones even though they were similar in volume. We believe that these findings, which are difficult to obtain experimentally, contribute to the understanding of the interfacial adhesion phenomena on a molecular scale.
AB - The composition of an epoxy resin at the interface with the adherend is usually different from that in the bulk due to the enrichment of a specific constituent, a characteristic called interfacial segregation. For better adhesion, it should be precisely understood how epoxy and amine molecules exist on the adherend surface and react with each other to form a three-dimensional network. In this study, the entropic factor of the segregation in a mixture of epoxy and amine at the copper interface before and after the curing reaction is discussed on the basis of a full-atomistic molecular dynamics (MD) simulation. Smaller molecules were preferentially segregated at the interface regardless of the epoxy and amine, and this segregation remained after the curing process. No segregation occurred at the interface for a combination composed of epoxy and amine molecules with a similar size. These findings make it clear that the size disparity between constituents affects the interfacial segregationviathe packing and/or translational entropy. The curing reaction was slower near the interface than in the bulk, and a large amount of unreacted molecules remained there. Finally, the effect of molecular shape was also examined. Linear molecules were more likely to segregate than round-shaped ones even though they were similar in volume. We believe that these findings, which are difficult to obtain experimentally, contribute to the understanding of the interfacial adhesion phenomena on a molecular scale.
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U2 - 10.1039/d0sm01600d
DO - 10.1039/d0sm01600d
M3 - Article
C2 - 33325969
AN - SCOPUS:85101453582
SN - 1744-683X
VL - 17
SP - 1359
EP - 1367
JO - Soft Matter
JF - Soft Matter
IS - 5
ER -