Dynamic properties of temperature-sensitive poly(N-isopropylacrylamide) gel cross-linked through siloxane linkage

A gel is a water-insoluble polymeric material though it can absorb a lot of water in its network structure. The poly(N-isopropylacrylamide) (PNIPA) ge l exhibits a change in volume in response to external temperature changes a nd this property is useful in many fields. In this manuscript, a novel PNIP A gel was synthesized by using ethylene triethoxy silane (ETEOS) as the cro ss-linking agent under acidic conditions. This siloxane incorporated PNIPA gel achieves a dramatically rapid response rate when the external temperatu re is changed. We suggest that the improvement of the response rate could b e due to the macroporous structure of the produced polymer network during t he polymerization/cross-linking process. This macroporous structure can pro vide interconnected water release channels and prevent the formation of a d ense, thick skin layer at the shrinking course. On the other hand, water ca n also diffuse into the polymer network through these water channels during the reswelling process.