Preparation, properties, and drug release of thermo- and pH-sensitive poly((2-dimethylamino)ethyl methacrylate)/poly(N,N-diethylacrylamide) semi-IPN hydrogels

In this paper, a series of semi-interpenetrating polymer network (semi-IPN) hydrogels based on poly((2-dimethylamino)ethyl methacrylate)/poly (N,N-diethylacrylamide) (PDMAEMA/PDEA) were synthesized by changing the initial PDMAEMA/DEA molar ratio at room temperature. The influence of this additive on the property of resulting PDEA hydrogels was investigated and characterized. The interior morphology by scanning electron microscopy (SEM) revealed that the semi-IPN hydrogels have interconnected porous network structures. The glass transition temperature (Tg) of the semi-IPN hydrogels was observed by differential scanning calorimetry (DSC). Equilibrium swelling ratio (ESR), swelling and deswelling dynamics of the hydrogels responding to temperature and pH were investigated in detail. Compared to PDEA, the semi-IPN hydrogels exhibited excellent mutative values in response to an alternation of the temperature and pH, and showed fast swelling and deswelling rates in response to temperature and pH change. The release behaviors of the model drug, aminophylline, were found dependent on hydrogel compositions and environmental temperature. These results suggest that the stimuli semi-IPN hydrogel have potential application as intelligent drug carriers.