Investigation of the synthesis and properties of the copolymeric hydrogels based on N-isopropyl acrylamide and acrylamidoazobenzene

A series of copolymers and their corresponding hydrogels were prepared essentially from N-isopropyl acrylamide (NIPAAm) and acrylamidoazobenzene (AAAB) at different molar ratios. The AAAB was synthesized in advance and verified by elemental analysis, 1H-, and 13C NMR techniques. The effect of AAAB contents on the thermal and ultraviolet response of the copolymer and their corresponding hydrogels was investigated. The results showed that a changed quantity of AAAB in the copolymers and hydrogels would only slightly affect their LCSTs and CGTTs. In addition, the copolymers and their hydrogels show good thermo- and photo-response due to NIPAAm structure and the cis-trans isomerization of azobenzene group upon UV irradiation. Furthermore, effects of AAAB contents on the physical properties and drug release behavior of the copolymeric hydrogels were also examined.