Lithium adipic acid modified multiwalled carbon nanotube reinforced PVA hydrogels with enhanced multifunctional properties

Poly(vinyl alcohol) (PVA)-based hydrogels have attracted considerable interest for flexible electronics, wearable devices, and soft energy storage systems owing to their excellent bio-compatibility and water-retention capability. However, their practical applications are limited by poor mechanical strength, inadequate electrical performance, and the agglomeration of carbon nanotubes within the polymer matrix. To address these challenges, PVA-based composite hydrogels reinforced with mono-lithium adipate (Li-AA) modified multi-walled carbon nanotubes (m-MWCNTs) (0.025–0.125 wt%) were successfully fabricated using a simple anti-freeze–thaw-free physical cross-linking strategy. Functionalization with lithium-adipate (Li-AA) effectively reduced nanotube agglomeration and improved interfacial compatibility with the PVA matrix, as confirmed by optical microscopy, TEM, and SEM analyses. DSC studies revealed enhanced crystallization behaviour, while FTIR and Raman spectroscopy confirmed strong inter-molecular hydrogen bonding between PVA and m-MWCNTs. Rheological studies demonstrated the formation of a robust solid-like visco-elastic network with a high storage modulus (~ 2 MPa), and nanoindentation results showed significant improvements in hardness and elastic modulus. Broadband dielectric spectroscopy further revealed enhanced dielectric properties and restricted polymer chain mobility. Overall, Li-AA functionalization promoted uniform nanotube dispersion, strong interfacial interactions, and efficient network formation, resulting in simultaneous enhancement of the thermal, mechanical, and electrical properties of PVA hydrogels. The developed composite hydrogel exhibits significant potential for advanced flexible electronics and soft energy storage applications.