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1 H NMR relaxation study of polymer‐solvent interactions during thermotropic phase transition in aqueous solutions
Author(s) -
Spěváček Jiří,
Hanyková Lenka
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.200351324
Subject(s) - thermotropic crystal , polymer , relaxation (psychology) , aqueous solution , methylene , chemistry , molecule , phase (matter) , solvent , phase transition , crystallography , chemical physics , materials science , analytical chemistry (journal) , organic chemistry , thermodynamics , physics , liquid crystalline , psychology , social psychology
The dynamic‐structural changes and polymer ‐ solvent interactions during the thermotropic phase transition in poly(vinyl methyl ether) (PVME)/D 2 O solutions in a broad range of polymer concentrations ( c = 0.1‐60 wt.‐%) were studied combining the measurements of 1 H NMR spectra, spin‐spin ( T 2 ) and spin‐lattice ( T 1 ) relaxation times. Phase separation in solutions results in a marked line broadening of a major part of polymer segments, evidently due to the formation of compact globular‐like structures. The minority (∼15%) mobile component, which does not participate in the phase separation, consists of low‐molecular‐weight fractions of PVME, as shown by GPC. Measurements of spin‐spin relaxation times T 2 of PVME methylene protons have shown that globular structures are more compact in dilute solutions in comparison with semidilute solutions where globules probably contain a certain amount of water. A certain portion of water molecules bound at elevated temperatures to (in) PVME globular structures in semidilute and concentrated solutions was revealed from measurements of spin‐spin and spin‐lattice relaxation times of residual HDO molecules.