Highly conductive, anti-freezing, and adhesive hydrogels containing pores constructed by cation–dipole interactions

Abstract

The low ionic conductivity of most hydrogels limits their application in various fields. Boosting ion conductivity in anion exchange membranes (AEMs) using dipole-ion interactions (electrostatic attraction between anions and neutral dipole molecules) with exceptional interaction energies of 20 to 200 kJ mol−1 is the best way to create ion channels in anion exchange membranes (AEMs). In this study, intending to increase the ionic conductivity of hydrogels, the antifreeze crosslinked PVA/PVP hydrogels (5, 10, and 15% Cr-PVA) were prepared using 1,10-dibromodecane (DBD) to crosslink PVA and PVP via SN2 reaction to create multiple pores morphology in the hydrogels by cation-dipole interactions. Moreover, the prepared hydrogels contain cationic groups facilitating ion transport through the hopping mechanism. There was a significant difference in ionic conductivity between the 10% Cr-PVA hydrogel (2.63 S m−1) and the PVA hydrogel (0.76 S m−1) at room temperature due to the multiple pores created with cation-dipole interaction. Despite excellent mechanical properties, 10% Cr-PVA at −20 °C (1.25 S m−1) has a higher ionic conductivity than most antifreeze conductive hydrogels. Eventually, the 10% Cr-PVA hydrogel with gauge factor 1.97 demonstrated the desired sensitive response performance for sensor applications.