Mechanical and Electrical Properties of Polymer Interfaces and Their Applications

Abstract

This dissertation focuses on several newly proposed polymer interfaces and their mechanical and electrical properties. First, this research provides a new solution to address the tough and stretchable adhesion between dissimilar soft materials. The tough adhesion results from the synergy of strong cohesion of molecular staples, topological entanglements between glassy polymer chains and rubbery polymer chains, and large dissipation in the bulk of adherends. The stretchability of the interface is attributed to the distribution of discrete glassy phases. Second, a composite material for an anti-icing application is designed. The composite contains a liquid deicer in the polymer network. When contacted with ice, thermodynamics dictates the mixture of deicer and ice, the dissolution of ice, and the absorption of mixed liquids into the network. The adhesion between the composite and ice shows a brittle-to-ductile transition at low temperatures. Third, this work demonstrates a polymeric p-n junction made of ion-rich but liquid-free elastomers and creates non-Faradaic elastomeric diodes and transistors for ionotronic circuits. The junction is reversibly adhered and stretchable. The electromechanical transduction of junctions enables power-free sensors. Fourth, a mimicry of the function of the eye is established through the combination of a tunable ionic lens, optoionic sensors, and ionic cables. Various optoionic sensors are fabricated to convert light into different ionic signals. A photosensitive skin is designed to be responsive to light and independent of deformation, and a photosensitive actuation is assembled to mimic the light-triggered reflex. Finally, this research develops a method to print a highly stretchable supercapacitor through the interpenetrating of a brittle percolating carbon network and a stretchable polymer network. The percolating carbon trapped by the polymer network provides a large surface area for the electrical double layer. The elastic deformation of polymer network slides and rotates the carbon particles to facilitate a large stretchability. The method is generic for making stretchable ionotronic devices. This dissertation brings the understanding of new polymer interfaces and broads the applications of several kinds of polymers.