Preparation of cross-linked PANI/PVA conductive hydrogels for electrochemical energy storage and sensing applications

The tunability of flexible electro-conductive polymer hydrogel by retaining the gel-ness and swelling nature with significant electrical conductivity remains a challenging problem. Conductive hydrogel (CH) should exhibit gel-like behavior with an appreciable conductivity. The combined property of gel and conductivity depends on the relative proportion of the constituent components. Herein, we present the detailed investigation on the effect of composition of polyvinyl alcohol (PVA) and polyaniline (PANI) on the structure and properties of PANI/PVA conducting hydrogels. We have prepared a series of hydrogel by varying the ratio of PANI and PVA. We have observed that the property of the PANI/PVA hydrogel significantly depends on the PANI content in the hydrogel. The detailed analysis based on XRD reveals that the peak intensity at 2 theta = 19.3 degrees has been decreased and the bandwidth has been increased with increasing PANI content, implying a decrease in the degree of crystallinity and enhancing amorphous nature. The interaction between PANI and PVA is also evident from the change in FTIR spectra of OH group. Detailed morphological analysis shows the formation of well-interpenetrated structure of PANI and PVA. Swelling study and current-voltage measurement in DI water and artificial tear fluid show composition dependent gel and conducting behavior, respectively. Tuning the composition of PVA and PANI results the blend to possess adequate "gel" with improved flexibility and "conducting" nature, required for a conducting hydrogel (CH). We have shown the application of hydrogel as an electrode material for supercapacitor with significant cyclic stability (similar to 95 % after 1000 cycles). We have also presented the viability of CH as an enzymatic glucose biosensor, with a significant LOD (similar to 0.001 mu M).