Topology-Driven Miscibility in Polymer–Nanoparticle Composites via Loop–Linear Graft Blends

Matrix free polymer-grafted nanoparticles (PGNs) with linear grafts are highly tunable and offer enhanced mechanical and rheological performance relative to conventional nanocomposites, owing to superior dispersion and interfacial interactions. Recent works also suggest that mixtures of non-concatenated ring (loop) and linear polymers can enhance miscibility through entropic mixing. However, a molecular-scale analysis of chain sizes, dynamics, and miscibility in blends of entangled linear and loop grafts in the presence of free linear matrix in polymer-nanoparticle composite (PNC) remains unexplored. In this work, a chemistry-specific coarse-grained molecular modeling framework is employed to examine how topological architecture and dynamic asymmetry can be leveraged to compatibilize polymer blends in PNCs.

Building on this framework, a 10 wt% nanoparticle-loaded PNC with a 50:50 ratio of loop to linear grafts on each nanoparticle (Loop/Lin-PNC) is benchmarked against PNCs with 100% linear or loop grafts, as well as matrix-free PGNs. Among all systems, the Loop/Lin-PNC exhibits greater swelling of loop grafts as they thread with both linear grafts and the linear matrix. The resulting increase in conformational entropy is consistent with enhanced miscibility, a higher PNC-to-matrix relative viscosity, and modest improvements in elastic modulus and toughness relative to the other PNCs. These trends are confirmed by quantitative analysis of entanglements-resolved across chain topologies.