A novel triple responsive copolymer hydrogels composed of 2-(dimethylamino) ethyl methacrylate and 2-(N-morpholino) ethyl methacrylate monomers were prepared through free radical polymerization. The structure and morphology of the hydrogels were examined by using infrared spectroscopy (ATR-IR) and scanning electron microscopy (SEM). It was found that poly (DMAEMAco-MEMA) hydrogels exhibited pH-dependent smart swelling and shrinking behavior in buffer solutions which is ascribed to the protonation/deprotonation of the tertiary amine pendant groups of both monomers. The copolymerization of more hydrophobic MEMA monomer with hydrophilic DMAEMA monomer created associated micro domain in the hydrogel structure which is able to induce reversible phase transition of the hydrogel. Therefore, poly (DMAEMA-co-MEMA) hydrogels displayed rapidly responses to the increasing temperature and divalent salt effects by shrink-type behavior. Such a multi-responsive network structure would be very beneficial for biomedical applications.

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