A highly stretchable carbon nanotube/reduced graphene oxide/ poly(dimethylsiloxane) composite with high thermal conductivity as a flexible strain sensor

Carbon nanotube (CNT) is an important filler for preparing poly(dimethylsiloxane) (PDMS)-based composite sensors with high thermal conductivity. However, CNT encounters challenges in terms of dispersion within the polymer matrix. In this work, a combined strategy was proposed to improve the dispersion of CNT, involving surface modification of CNT, CNT-reduced graphene oxide (rGO) hybridization and in-situ cross-linking of PDMS in a solution. The in-situ cross-linking of PDMS contributed to an increase in elongation at break, coupled with a reduction in the modulus of the resulting in-situ crosslinked PDMS/m-CNT@rGO (S-PDMS/m-CNT@rGO) composites. Through the implementation of this strategy, the dispersion of CNT within the PDMS matrix was enhanced, simultaneously facilitating the establishment of filler networks. At the filler content of 10.0 wt%, the thermal conductivity of the S-PDMS/m-CNT@rGO composite increased to 1.06 W/(m·K) and the electrical conductivity increased to 4.51 × 10−3 S/cm. The S-PDMS/m-CNT@rGO composite had a low percolation threshold which was 0.35 wt%. When utilized as a strain sensor, the S-PDMS/m-CNT@rGO composite exhibited high sensitivity, good repeatability and stability in monitoring human motion.