The crosslinked copolymers and terpolymers of N ‐isopropyl acrylamide (NIPAm) with sodium‐2‐acrylamido‐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°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°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°C.
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Emik et al. (2006) studied this question.
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