Synthesis and swelling behavior of thermosensitive poly(N-isopropyl acrylamide-co-sodium-2-acrylamido-2-methyl propane sulfonate) and poly(N-isopropyl acrylamide-co-sodium-2-acrylamido-2-methyl propane sulfonate-co-glycidyl methacrylate) hydrogels

The crosslinked copolymers and terpolymers of N-isopropyl acrylamide (NIPAm) with sodium-2acrylamido-2-methyl propane sulfonate (NaAMPS) and glycidyl methacrylate (GMA) were prepared in the presence of N,N'-methylene bisacrylamide (NMBA) as crosslinker by free radical solution polymerization at 4 degrees C. Potassium persulfate (KPS) and potassium bisulfide (KBS) were used as initiator and accelerator, respectively. While molar percentages of NaAMPS in copolymers feed were varied as 1, 2, and 3; NaAMPS and GMA were used in the molar percentages of 1 : 1, 2: 2, and 3: 3, respectively, for the terpolymer preparation. NMBA contents were kept constant as 1 or 1.5 mol % of total monomer moles in feed composition. The effects of the comonomer type, feed composition, and the crosslinker contents on the lower critical solution temperatures (LCST), equilibrium swelling values (Q) of polymers, swelling kinetics in water at room temperature, and deswelling kinetics at 55 degrees C were investigated. The results indicated that the higher the NaAMPS content in NIPAm/NaAMPS copolymer, the higher the Q and water uptake rate, but less the water release rate. However, the presence of hydrophobic GMA comonomer in the terpolymer of NIPAm/NaAMPS/GMA decreased the Q values, it increased both the water uptake and the water release rates. It was also observed that NIPAm/NaAMPS and NIPAm/NaAMPS/GMA polymers exhibit continuous phase transition behavior between 40 and 50 degrees C. (c) 2006 Wiley Periodicals, Inc.