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Polymer‐solvent interactions during phase transition in poly(vinyl methyl eiher)/D 2 O solutions as studied by NMR methods
Author(s) -
Spěváček Jiři,
Hanyková Lenka,
Ilavský Michal
Publication year - 2001
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 - 10.1002/1521-3900(200103)166:1<231::aid-masy231>3.0.co;2-e
Subject(s) - polymer , lower critical solution temperature , molecule , solvent , phase transition , ether , polymer chemistry , materials science , phase (matter) , chemistry , organic chemistry , copolymer , thermodynamics , physics
The structural‐dynamic changes and polymer‐solvent interactions during temperature‐induced phase transition in poly(vinyl methyl ether) (PVME)/D 2 O solutions in a broad range of concentrations (0.1‐30 wt.‐%) were studied by 1 H NMR methods. In the whole concentration range the phase transition is manifested by line broadening (linewidth 350‐500 Hz) of a major part of PVME units, evidently due to the formation of globular‐like structures. Above the LCST transition, the fraction of phase‐separated PVME segments is equal to 0.8±0.1, independent of polymer concentration. While at low concentrations the transition is virtually discontinuous, at high concentrations the transition region is ∼ 3 K broad. Measurements of nonselective and selective 1 H spin‐lattice relaxation times T 1 of solvent (HDO) molecules evidenced that at elevated temperatures, where most PVME forms globular structures, a part of solvent molecules is bound to PVME forming a complex; the lifetime of the bound water (HDO) molecules is ≤2 s.