This letter describes the phase behavior of aqueous solutions of an N-isopropylacrylamide (NIPAM) homopolymer and copolymers of N,N?- diisopropylfumaramide (DIPFAM) and NIPAM as studied by transmittance measurements, infrared spectroscopy, and differential scanning calorimetry to reveal the effect of the density of N-isopropylamide side chain upon the phase behavior. The clouding-point and clearing-point temperatures decreased with increasing the mole fraction of DIPFAM (x D). It was noteworthy that only an extra side chain per ca. 7 NIPAM units had a remarkable effect on the phase behavior; the interactions between side chains were stronger, the intrapolymer contraction was less favorable, and the cooperativity of phase transition was lower at x D = 0.15 presumably because of the steric hindrance of dense side chains.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Surfaces and Interfaces