Electric field-assisted annular arrangement of sulfonated polystyrene particles for isotropically enhanced matrix performance.

An ordered and rationally designed distribution structure can fully exploit the superior properties of micro/nano-fillers, maximizing the synergistic effects between the fillers and the matrix. However, current research primarily focuses on the linear alignment of fillers, which only enhances the composite's performance along a specific direction. In this study, sulfonated polystyrene (SPS) particles were arranged in an annular pattern induced by an electric field. Similar to the role of aggregates in concrete, the oriented SPS particles acted as rigid support points, constructing "micro-bridges" within the matrix. These SPS particles cooperatively bore the load with the matrix, reducing stress concentration and enabling the composite to exhibit improved integrity and stability. In tensile tests, hydrogels containing 1 wt% oriented particles demonstrated an approximately 68.5% increase in fracture elongation and a 7.67 kPa enhancement in tensile strength compared to the pure polyacrylamide hydrogel. This study introduces a novel filler annular orientation strategy that enables isotropic enhancement of composite properties while effectively overcoming the limitations imposed by conventional direction-dependent reinforcement mechanisms.