Molecular dynamics simulations of vinyl ester resin monomer interactions with a pristine vapor-grown carbon nanofiber and their implications for composite interphase formation Original Research Article

A molecular dynamics simulation study was performed to investigate the role of liquid vinyl ester (VE) resin monomer interactions with the surface of pristine vapor-grown carbon nanofibers (VGCNFs). These interactions may influence the formation of an interphase region during resin curing. A liquid resin having a mole ratio of styrene to bisphenol-A-diglycidyl dimethacrylate VE monomers consistent with a commercially available 33 wt.% styrene VE resin was placed in contact with both sides of two pristine graphene sheets overlapped like shingles to represent the outer surface of a pristine VGCNF. The relative monomer concentrations were calculated in a direction away from the graphene sheets. At equilibrium, the styrene/VE monomer ratio was higher in a 5 Å thick region adjacent to the nanofiber surface than in the remaining liquid volume. The elevated concentration of styrene near the nanofiber surface suggests that a styrene-rich interphase region, with a lower crosslink density than the bulk matrix, could be formed upon curing. Furthermore, styrene accumulation in the immediate vicinity of the nanofiber surface might, after curing, improve the nanofiber–matrix interfacial adhesion compared to the case where the monomers were uniformly distributed throughout the matrix.