Thermosensitive poly (N-isopropylacrylamide) hydrophobic associated hydrogels: optical, swelling/deswelling, and mechanical properties

Thermosensitive hydrophobic associated hydrogels (NI-HA gels) were prepared by free radical micellar copolymerization in aqueous solution of N-isopropylacrylamide, a small amount of hydrophobic monomer octylphenol polyoxyethylene (4) acrylate (OP4 similar to AC), and nonionic surfactants. The mechanical properties, swelling/deswelling behaviors, and optical transmittances of NI-HA gels were studied. As OP4 similar to AC content varied, both mechanical properties and swelling behaviors of gels changed greatly. The temperature-induced changes in optical transmittance and deswelling tests showed that NI-HA gels had rapid temperature responsive rate and clear volume phase transitions at around 34 degrees C, and these properties had almost no concern with OP4 similar to AC content. Furthermore, NI-HA gels also possessed extremely sensitive swelling/deswelling switch behaviors and well swelling stabilities.