Thermoresponsive microhydrogels: Preparation, properties and applications

Abstract

The dispersion stability of PNIPAM microhydrogels is controlled by temperature and salt concentration (A). PNIPAM microgels formed a 2-D colloidal crystal (B) and emitted structural color (C) Cells are happy on a PNIPAM gel sheet althrough damaged by a rigid PSt particle sheet (D). 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. © 2013 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.