Electrically conductive polyacrylamide/carbon nanotube hydrogel: reinforcing effect from cellulose nanofibers

The development of polymeric hydrogels with new functionalities is becoming an aspiration in various fields. Here we report a simple method to fabricate a conductive polyacrylamide (PAM)-based hydrogel by the incorporation of carbon nanorubes (CNTs). However, the major challenge for these hydrogels is CNT aggregation in PAM, which decreases both mechanical and electrical properties of the composite hydrogels. Inclusion of cellulose nanofibers (CNFs), is expected to disperse the CNTs well, thereby reinforcing the PAM hydrogels. Hence, by mixing the CNFs and CNTs in the AM hybrid solutions, a PAM/CNF/CNT composite hydrogel is prepared through in situ polymerization. Specifically, with incorporation of 1 wt% CNF and 1 wt% CNT into PAM, the PAM/CNF/CNT-1 hydrogel, with an electrical conductivity of 8.5 × 10⁻⁴ S/cm, shows a threefold higher fracture tensile strength than the pure PAM hydrogel. Given the improved mechanical properties and electrical conductivity, the use of CNF as a reinforcing agent for both PAM and CNT provide a versatile method to fabricate conductive hydrogels, and has potential to expand their application in the field of bio-medical engineering and electrical devices.