Abstract
Incorporation of carbon allotropes of different dimensions within elastomeric matrices has been established as an effective strategy to fabricate functional conductive polymer nanocomposites (PNCs). In this work, higher-dimensional 3D hybrid carbon nanofillers, comprising synergistically integrated multiwalled carbon nanotubes immobilized onto few-layer graphene, were incorporated into the thermoplastic polyurethane (TPU) matrix to demonstrate their effectiveness as strain sensors. The conductive films were fabricated through a simple solution casting technique, in which the mechanical, electrical, and strain-sensing characteristics were studied in view of filler distribution, structural confinement, and interfacial interactions. Analyses using wide-angle X-ray scattering, Raman spectroscopy, and tensile testing revealed a higher degree of filler reinforcement within the TPU moieties, indicating pronounced interfacial interactions. Further, the tensile modulus increased significantly with filler loading above its percolation threshold (363% for 20 wt % loading). The structural features of dispersed filler aggregates were explored through an iterative model fitting of the ultra-small-angle X-ray scattering (USAXS) data, along with scanning electron microscopy (SEM). As a strain sensor, the films displayed a superior working-strain Gauge Factor (GF = 123, up to 8%), with exceptional stability under both unidirectional and cyclic strain. The findings provide a fundamental understanding while validating the potential of hybrid carbonaceous fillers for the fabrication of PNCs with futuristic applications.