Engineering a Bimodal Multicore Dispersed Phase Structure for Low-Temperature Toughening of Polymer Nanocomposites

Polymer nanocomposites (PNCs) are often constrained by inadequate nanoparticle dispersion, weak interfacial interactions, and the resultant deterioration in melt processability and low-temperature brittleness. Herein, we fabricate a polypropylene/polystyrene- b -ethylene-propylene- b -polystyrene/ethylene-propylene rubber/nanosilica (PP/SEPS/EPR/SiO 2 ) composite with a controllable bimodal-distribution multicore (BDM) structure using polystyrene (PS) as a nanogrinding medium. The PS nanodomains are found to effectively break up the agglomeration of SiO 2 nanoparticles and hinder their migration to the interface, leading to the selective localization of SiO 2 within the dispersed phase of the BDM structure. This enhances the process flowability and significantly strengthens the cavitation-suppressing effect of the complex dispersed phase. Based on this mechanism, the BDM structure delays craze propagation, improves impact-bearing capacity, and increases total energy absorption at low temperatures, all without significant compromise in strength. By constructing more sophisticated dispersed-phase structures and controlling the directional distribution of nanoparticles, this work provides an efficient, low-consumption strategy for producing PNCs with superior low-temperature toughness.