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1 H NMR study of phase transition of uncharged and negatively charged poly( N ‐isopropylmethacrylamide) in D 2 O solutions
Author(s) -
Starovoytova Larisa,
Spěváček Jiří,
Hanyková Lenka,
Ilavský Michal
Publication year - 2003
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200351325
Subject(s) - comonomer , polymer , ionic bonding , phase transition , phase (matter) , methacrylate , analytical chemistry (journal) , copolymer , mole fraction , chemistry , ionization , globular cluster , transition temperature , materials science , polymer chemistry , ion , chromatography , organic chemistry , thermodynamics , physics , superconductivity , quantum mechanics , galaxy
1 H 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 D 2 O 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.