Ultrafast Responsive Poly- (N-isopropylacrylamide) Gel Produced by Cryostructuring of Self-crosslinkable Polymer Microgels.

A macroporous material composed of closely aggregated particles was prepared by cryo-structuration of N-isopropylacrylamide-co-N-hydroxymethylacrylamide (NIPA-co-HMAm) particle suspensions. The formed structure was maintained by the formation of covalent bonds through self-crosslinking between the particles while the system was in a semi-frozen state thus avoiding the need to freeze-dry the sample. This resulted in macroporous structure composed of closely aggregated thermoresponsive particles which exhibit an ultrafast temperature response. The response rate can be attributed both to the macroporous structure as well as the fast responsive properties of the individual particles.