A Meso-scale Simulation Study of Short-range Morphologies and Properties of Thermoplastic Polyurethane Affected by Graphene Nano-fillers under External Flow

Embedding nanofillers into polymers is crucial to improving the engineering properties of these materials. Recent computational approaches have paved the way for bridging the gap between the microstructure and macroscopic properties of materials. Our group has performed mesoscale Dissipative Particle Dynamics simulations to investigate the effect of incorporation of Graphene Nanosheets (GNs) on morphologies and mechanical properties of Thermoplastic Polyurethane (TPU). In particular, we have investigated the effects of local interactions, compositions, and chemistry of components on the final morphologies of materials. Our observations show that GNs can potentially act as a nucleating agent leading to crystallization of TPU at nanosheet surface. These crystalline domains connected with regions of soft segments are speculated to be the morphological origin of experimentally observed enhancements in mechanical properties. Under quiescent conditions, Flory-Huggins χ parameters between hard-soft segments, TPU compositions, and surface chemistry of GNs are critical factors dictating final morphologies. Additionally, the simple shear flow is applied to investigate the effect of shear rate on final morphologies. Our findings can benefit the design and fabrication of TPU nanocomposites.