Polyvinyl alcohol/chitosan/carbon nanotubes electroactive shape memory nanocomposite hydrogels

Shape memory nanocomposite hydrogels are intelligent soft materials in which, the nanoparticles can impart desirable mechanical properties to the polymeric matrix. The main challenge is the capability to program from permanent to temporary shapes and vice versa under the direct and indirect thermal stimuli. In this work, carbon nanotubes (CNT) with a high modulus of 1 TPa, was used to mechanically reinforce polyvinyl alcohol (PVA) and polyvinyl alcohol/chitosan (PVA/Cs) hydrogel networks. Adding appropriate amount of conductor component enables the system to be electrically activated, which leads to achieving the original permanent shape without applying mechanical external force. The PVA/Cs/CNT hydrogel containing 0.25 wt% of CNT, showed electrical conductivity greater than 9 mS cm⁻¹. Because of the presence of CNT, the shape memory behavior of PVA and PVA/Cs hydrogels was improved by 170 and 260%, respectively. The electroactive shape memory nanocomposite hydrogels exhibited complete recovery under indirect stimulation by generating Joule heating in the system.