Rapid Swelling/Collapsing Behavior of Thermoresponsive Poly(N-isopropylacrylamide) Gel Containing Poly(2-(methacryloyloxy)decyl phosphate) Surfactant

摘要

Poly(N-isopropylacrylamide) (PNIPA) gel has attracted considerable attention, from both the academic and technological viewpoints. PNIPA gel undergoes an abrupt volume change at the phase-transition temperature (ca. 34 ℃), which can be utilized in several promising applications such as drug delivery systems and actuators. For better performance of these applications, several strategies have been reported to exploit the rapid volume change of PNIPA gels. However, PNIPA gel also exhibits salt-tolerant water absorbency through the incorporation of surfactants such as sodium dodecyl sulfate (SDS). The behavior of the PNIPA gel in surfactant solutions has been extensively studied, but little research has been reported on PNIPA gels containing polymeric surfactants. In our studies, poly(2-(methacryloyloxy)decyl phosphate) (PMDP) was chosen as the polymeric surfactant, which was expected to afford a superabsorbent PMDP-containing PNIPA (PNIPA-PMDP) gel in the presence of salts. The PNIPA-PMDP gel did not exhibit superabsorbency in sodium chloride solutions, but interestingly showed a rapid volume change above its phase transition temperature when compared to conventional PNIPA gels. Herein, we report the rapid volume change of PNIPA-PMDP gels as a function of temperature as well as by laser-beam irradiation. Our results clearly demonstrate the PMDP-induced enhancement of the response dynamics for the polymeric network of PNIPA gels.