Hydrophilic, transparent, and stretchable film using unmodified cellulose fibers

As interest in wearable devices increases, much research has focused on stretchable polymers. However, most semiconductor materials used in such devices are hydrophilic and stretchable polymers are hydrophobic, which arises an adhesion problem at their interfaces. In addition, most of these polymers are not biodegradable, which creates environmental problems. In this study, in order to avoid these two problems, we used cellulose, the most abundant natural polymer on earth, as a framework, and chemically cross-linked cellulose chains with epichlorohydrin to provide elasticity to the film. As a result, this hydrophilic film stretched to 196% and was insoluble in solvents. It also had the optical transmittance of 90% in the visible region.