Molecular Dynamics Simulations of Vinyl Ester Resin Monomer Interactions with a Pristine Vapor-Grown Carbon Nanofiber and Their Implications for Composite Interphase Formation

Nouranian, S., Jang, C., Lacy, T., Gwaltney, S. R., Toghiani, H., & Pittman, C. (2011). Molecular Dynamics Simulations of Vinyl Ester Resin Monomer Interactions with a Pristine Vapor-Grown Carbon Nanofiber and Their Implications for Composite Interphase Formation. Carbon. 49(10), 3219-3232. DOI:10.1016/j.carbon.2011.03.047.

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 removed 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.