Oral: Elucidating nanoparticle reinforcing effects through low-volume chemical coupling as explored by coarse-grained molecular dynamics

The addition of linker molecules with varying topology and stoichiometry into a carbon nanotube (CN)-reinforced polymer composites exhibits pronounced morphological differences and resulting rheological properties compared to CN-reinforced only controls. The underlying mechanism of action is complex because the mesoscale properties evolve over a broad range of interrelated lengths and time scales. These originate at the local structure of the crosslinking junction, extending into the segmental motion in the Kuhn length regime and finally influencing the large-scale diffusive motions proportional to the radius of gyration. In this study, we present an easily scalable approach to elucidate the effect of linker topology and stoichiometry on the segmental dynamics and bulk properties in a covalently bonded CN polymer composite. We performed a series of coarse-grained molecular dynamics (CGMD) simulations to investigate the morphological and rheological performance of polymers in response to linker topology and crosslink reactions. Our CGMD results indicate that the degree of matrix phase separation is positively correlated with polymer segmental diffusivity, which can be limited through increasing linker rigidity and cross-linking. The CGMD results, which agree well with experimental measurement, can provide guidelines for the a priori design of CN-reinforced composite materials.