Polyvinyl alcohol incorporated buckypaper composites for improved multifunctional performance

Carbon nanotubes (CNT) and graphene have been recognized as superior nanomaterials for high-performance, lightweight and multifunctional composites. However, non-uniform CNT/graphene dispersion within the polymer matrix, imperfect interphase between CNT/graphene and polymer matrix have hindered significant improvements in composite performance. In this study, we present a water-based grafting approach to produce polyvinyl alcohol (PVA) incorporated CNT buckypaper and CNT-graphene hybrid buckypaper composites with enhanced mechanical performance (tensile and fracture) and electrical conductivity. Our approach provides a wide range of composition for CNT (5–77 wt.%) and PVA matrix (23–95 wt.%) without compromising the uniformity of CNT dispersion and polymer matrix homogeneity. The composite buckypapers have lightweight with a density of 168 mg/cc (lighter than daily use copy papers having a density of 740 mg/cc). They show an electrical conductivity of 82 S/cm which is five orders higher than the neat PVA films (10⁻⁵ S/cm) and three orders higher than the previous reports. Overall, 600% improvement in the Young's modulus and 80% improvement in the tensile strength with an optimum PVA loading is observed. They also exhibit a strong linear piezoresistive response. The water absorption changes their mechanical (tensile and Mode I fracture), electrical and piezoresistive performance. The cross-sectional fracture SEM images are used to understand the failure mechanisms. The results suggest that the developed approach would be an effective method for the fabrication of high-performance, lightweight, multifunctional composite buckypaper.