Preparation and Properties of Temperature-Responsive Hydrogels Based on Acylhydrazone Reversible Covalent Bonds

A series of PAM-co-PDAAM-co-PNIPAM copolymers were synthesized by reversible addition fracture transfer (RAFT) polymerization from acrylamide (AM), diacetone acrylamide (DAAM) and N-isopropylacrylamide (NIPAM). Their structure and composition were characterized by Nuclear Magnetic Resonance (NMR) and Gel Permeation Chromatography (GPC). Hydrogel with pH and temperature dual-response formed by the acyl hydrazone dynamic bonds between ketocarbonyl in polymer and hydrazide in adipic dihydrazide (ADH). The dual-responsive behavior of hydrogels to temperature and pH was researched by rheological measurement, Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy. At the same time, the hydrogel demonstrated temperature controlled self-healing properties. Besides, the hydrogels showed pH-and temperature-responsive controlled release behaviors for doxorubicin(Dox).