Synthesis and characterization of thermally-sensitive polymer: Poly(aminomethoxypropylacrylamide)

In this study, a temperature sensitive polymer was obtained by the solution polymerization of 2-amino-1-methoxypropylacrylamide. The monomer, 2-amino-1-methoxypropylacrylamide was synthesized by the nucleophilic substitution reaction of N-2-amino-1-methoxypropane and acryloyl chloride. The solution polymerization was performed in ethanol at 70 °C by using azobisisobutyronitrile as the initiator. Poly(2-amino-1-methoxypropylacrylamide), PAMPA, exhibited a reversible phase transition behavior by the temperature in the aqueous medium. The effects of polymer and salt concentrations on the lower critical solution temperature and critical flocculation temperature were investigated. The lower critical solution temperature values were 56.5, 46.5, 43.5 and 35.0 °C for 0.1, 0.5, 1.0 and 5.0 wt.% PAMPA solutions in aqueous media, respectively. These results indicated that lower critical solution temperature is dependent on the polymer concentration. It was also found that critical flocculation temperature for 0.1 wt.% PAMPA concentration decreased from 52.5 °C to 35.0 °C and for 1.0 wt.% PAMPA from 47.5 °C to 28.5 °C in salt concentrations. The effect of salt concentration on the critical flocculation temperature of poly(2-amino-1-methoxypropylacrylamide) was reasonably similar to that of poly(isopropylacrylamide). In ethanol–water media, the reversible phase transition behavior was observed up to the ethanol concentration of 30% (v/v). This study indicated that poly(2-amino-1-methoxypropylacrylamide) was an alternative thermally reversible material for poly(isopropylacrylamide).