Adopted ion-pair effect to construct bicontinuous starch-based gel and its application in humidity sensitivity and strain-responsiveness

Abstract

Along with the growing consume of disposable electronic devices, the development of biodegradable and sustainable resources is highly desired to address the contaminated footprints from petroleum-based materials. However, it is still a challenge to overcome obstacles of the dispersion of additives and flexibility for fabricating starch-based strain-responsiveness device. Herein, we developed a facile method to fabricate mechanically stretchable starch-based gel (SGZn gel) with humidity-conductivity through thermal mixing starch and ions-pairing solution, which was a kind of transparent gel without region of stress concentration and hysteresis effect. Attributed to disorganization effect and dipole interaction of ion pairs, SGZn gels achieved homogeneous matrix, increased elongation at break (243%) and high transparency (87%). Meanwhile, the continuous ionic conductivity paths in gel matrix constructed by ions-pairing solution could endow SGZn gels with excellent humidity sensitivity, obtaining an ionic conductivity of 10−3 S/cm after absorbing 10 wt% water from humidity environment. Benefiting from these features, SGZn gels were capable of sensing human motions, both tiny motion in fingers and intense force in feet, satisfying the basic requirements for sustainable wearable devices. This study provided a facile approach for preparing multifunctional starch-based gels to meet the requirements in various applications such as flexible material, humidity detection and smart devices.