Development of Photoreactive Units in Photoprocessable Polymer Network Materials

Abstract

Photoprocessable polymer network materials undergo changes in their shape and stiffness via the cleavage of covalent bonds in the polymer chains or cross-linkers under light irradiation. Owing to their high spatiotemporal resolution, they are used in various applications, including photolithography, drug delivery, and adhesives. Recently, various types of photoreactive moieties in the polymer networks have been developed, allowing low-energy, rapid, and reversible photoprocessing. Moreover, a new class of photoreactivity enables higher-order material control by utilizing multiple stimuli, in addition to light. The reactivity of materials to light can be tuned and switched by sequential or simultaneous treatments with chemical reagents. This sophisticated photoreactivity would expand the applications of photoprocessable materials because these materials can be used even in a lit environment without undesired photoreactions. In this review, we summarize the recent progress in photoprocessable polymer network materials based on the chemical cleavage of polymer chains under light, focusing on the molecular design of the photoreactive moieties.