Carbon nanotube-geopolymer nanocomposites: A molecular dynamics study of the influence of interfacial chemical bonding upon the structural and mechanical properties

Although carbon nanotube (CNT) is an excellent additive in geopolymer, the effect of its chemical bonding at interfaces is not well understood. This paper explores the effects of interfacial bonding on the structure, dynamics and mechanical properties of CNT-geopolymer nanocomposites via molecular dynamics simulations. Our findings from the structural analysis reveal that the interfacial bonding decreases the thickness of the interfacial van der waals (vdW) excluded volume and interphase (inner) region, and condenses the interfacial structure. Remarkably, it is found that the interfacial bonding provides a new restrictive mechanism limiting the diffusion of components in the geopolymer matrix. A dynamical heterogeneous character is found as the atom mobility of the inner region is slower than that of the outer region. Furthermore, the pull-out test reveals about 15 times increase in the interfacial shear strength of CNT-geopolymer nanocomposite with 10.0% interfacial bonding concentration, which is beneficial for the enhancement of its mechanical properties and hinders crack formation under tensile loading. The tensile test reveals about 60% and 80% increase in the nanocomposite's Young's modulus and tensile strength, respectively. This study provides, for the first time, valuable insight into the role of the interfacial bonding on the performance of CNT-geopolymer nanocomposites. (C) 2020 Elsevier Ltd. All rights reserved.