Abstract 1H NMR spectroscopy has been applied to the analysis of dynamic‐structural changes during temperature‐induced phase transition of non‐ionized poly(N‐isopropylmethacrylamide) (PIPMAm) and ionized copolymers of N‐isopropylmethacrylamide with sodium methacrylate, all in D2O solutions with various polymer concentrations (c = 0.1‐10 wt.‐%) and ionic comonomer mole fractions (i = 0‐10 mole %). It was found that the formation of compact globular‐like structures during the phase transition is independent of polymer concentration for non‐ionized samples; the presence of negative charges on the polymer chains leads to a dependence of the phase transition temperature on c and i. Virtually all PIPMAm segments are in globular‐like structures for low polymer concentrations; for c ⩾ 1 wt.‐%, this holds only for low content i of the ionic comonomer. An increase in c and i leads to a decrease in the fraction of polymer segments in globular‐like structures; for samples with highest values of c and i, the phase transition was not observed.
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Starovoytová et al. (2003) studied this question.