Investigation of real-time stress-induced self-organization of nanofillers in stretchable nanocomposites: state of the art and future perspectives

Abstract

Maintaining the structural stability and electrical conductivity of self-assembled nanofiller assemblies in stretchable polymer matrix under repeated mechanical deformation remains a central challenge in the development of reliable flexible electronic devices. Cyclic bending often induces dynamic reorganization of conductive nanofillers within elastomeric matrices, leading to progressive disruption of percolated pathways and a concomitant increase in electrical resistance. Here, we present a comprehensive real-time analysis of stress-induced self-organization and network formation of conducting nanofillers using in-situ mechanical deformation and thermal annealing. Simultaneous electrical conductivity measurements were performed during film stretching inside a synchrotron-based ultra-small-angle X-ray scattering instrument. This multimodal approach enables direct visualization of hierarchical nanofiller assembly and restructuring across multiple length scales under periodic stress. By systematically exploring a diverse set of polymer matrices and conductive fillers with distinct geometries and surface functionalities, we elucidate the intra- and intermolecular reinforcement mechanisms that mitigate shear-induced damage, stabilize interpenetrating networks, and delay conductive network fragmentation. Our findings highlight the critical role of non-bonded polymer-filler and filler-filler interactions near the percolation threshold in governing electromechanical durability. These insights provide a rational framework for designing mechanically robust, strain-tolerant conductive nanofiller inks and nanocomposites for next-generation flexible and wearable electronic applications.