Effects of internal microstructures of poly(N-isopropylacrylamide) hydrogels on thermo-responsive volume phase-transition and controlled-release characteristics

摘要

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels were fabricated with distinctly different internal microstructures. The internal microstructures of the PNIPAM hydrogels were characterized by SEM, and the effects of the internal microstructures of the PNIPAM hydrogels on their thermo-responsive volume phase-transition and controlled-release characteristics were experimentally investigated. The results showed that there were two kinds of microstructures of PNIPAM hydrogels, a homogeneous netlike microstructure and a heterogeneous microstructure with microgel clusters, and the thermo-responsive volume phase-transition behaviors and controlled-release characteristics of the PNIPAM hydrogels were found to be heavily dependent on their internal microstructures. The homogeneous internal microstructure caused a remarkably greater volume change, while the heterogeneous internal microstructure resulted in a more rapid responsiveness and a more ideal thermo-responsive controlled-release property. Consequently, for different applications, PNIPAM hydrogels should be designed and fabricated with different internal microstructures.