Interfacial Binding Energy between Calcium-Silicate-Hydrates and Epoxy Resin: A Molecular Dynamics Study.

Xianfeng Wang,Wei Xie,Jihua Zhu,Feng Xing,Long-Yuan Li,Jun Ren

doi:10.3390/polym13111683

Xianfeng Wang, Wei Xie + Show 4 more

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https://doi.org/10.3390/polym13111683

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Abstract

Microcapsules encapsulated within epoxy as a curing agent have been successfully applied in self-healing materials, in which the healing performance significantly depends on the binding behaviour of the epoxy curing agent with the cement matrix. In this paper, the binding energy was investigated by molecular dynamics simulation, which could overcome the shortcomings of traditional microscopic experimental methods. In addition to the construction of different molecular models of epoxy, curing agents, and dilutants, seven models were established to investigate the effects of chain length, curing agent, and epoxy resin chain direction on the interfacial binding energy. The results showed that an increase of chain length exhibited had limited effect on the binding energy, while the curing agent and the direction of the epoxy significantly affected the interfacial binding energy. Among different factors, the curing agent tetrethylenepentamine exhibited the highest value of interfacial binding energy by an increment of 31.03 kcal/mol, indicating a better binding ability of the microcapsule core and the cement matrix. This study provides a microscopic insight into the interface behaviour between the microcapsule core and the cement matrix.

Highlights

As the most widely used building material worldwide [1], the safety and service life of concrete is important
The COMPASS force field is used to describe the interaction between atoms, which is an ab initio force field, and its algorithm is largely derived from the early force field, namely the CFF force field
It can beStructural seen from the table that after molecular dynamics (MD) simulation, the length of all models in the Z direction

Summary

Introduction

As the most widely used building material worldwide [1], the safety and service life of concrete is important. During its service life, microcracks or defects inevitably occur in concrete Without proper control, this may lead to a serious impact on the structures, and further reduce the durability and shorten the service life of the structures [2,3]. This may lead to a serious impact on the structures, and further reduce the durability and shorten the service life of the structures [2,3] To solve this issue, many scholars have attempted to repair microcracks by employing various methods [4,5,6,7]. Compared with traditional repairing technology, the microcapsule self-healing system exhibits the advantages of automatic repair, low cost, and renewability. This self-healing system is designed based on three steps to achieve the repairing effect: (1) embedding the encapsulated healing agent in the cement matrix, (2) releasing the healing agent after the breaking of the container when the matrix produces microcracks, and (3) bonding the cementitious matrix with the cured healing agent to block the microcracks [9]

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