Thermoresponsive microhydrogels: preparation, properties and applications

A microgel is a fascinating type of soft matter. Among the various microgels, great interest has been shown in microhydrogels because their functions are realized in water, which is the most benign liquid to humans. The microhydrogel‐composing polymers have their own delicate hydrophilic − hydrophobic balance, which is sensitive to environmental conditions such as temperature, pH , ionic strength, light and specific (bio)molecules, in many cases. This review describes the methodology for the preparation of such microhydrogels, their properties, and finally their applications in physicochemical, biological and biomedical, optical and photonic, and chemical fields. The main material cited is a representative temperature‐sensitive polymer, poly( N ‐isopropyl acrylamide), but some other environment‐friendly polymers such as cellulose derivatives are also reported.