Polytetrahydrofuran Amphiphilic Networks, 5. Synthesis and Swelling Behavior of Thermosensitive Poly(N-isopropylacrylamide)-l-polytetrahydrofuran Networks

Abstract

A series of thermosensitive and thermoreversible poly(N-isopropylacrylamide)-l-polytetrahydrofuran (PNIPAAm-l-PTHF) amphiphilic networks were synthesized by free-radical copolymerization of N-isopropylacrylamide with the macromolecular crosslinker polytetrahydrofuran diacrylate (PTHFDA). The resulting PNIPAAm-l-PTHF networks show not only the properties of PNIAPPm and PTHF segments, but also the combined properties of the two segments. These networks are amphiphilic and their swelling is composition-dependent both in water and in organic solvents. The relationship of their equilibrium swelling ration (SR e ) and the content of network (W PTHF ) in organic solvents can be defined as: SR e = A* W PTHF + B. They present four solubility parameters that correspond to the hydrophobic and hydrophilic segments of networks. The swelling dynamics of the networks in water in a non-Fickian process, while in cyclohexane they approaches a Fickian process when the PTHF content is about 50-60%. Due to the presence of PTHF segments, the temperature effect on the swelling behavior of the PNIPAAm-l-PTHF networks is significantly different from other reported PNIPAAm copolymers or networks .The thermosensitivity and thermoreversibility of these networks is composition-dependent.