Abstract
Collapse of a gel prepared from an oxyethylene-oxypropylene copolymer was studied by measuring the temperature dependences of spin-lattice and spin-spin relaxation times; the copolymer network was prepared by a reaction between thiol end groups of a three-star oligomer. The collapse manifests itself by a sudden drop of the segmental mobility of macromolecules as well as of rotational mobility of water molecules. The observed strong decrease of the self-diffusion coefficient of water is not due to the sudden rise of polymer concentration, but results from a displacement of water into micropores in the collapsed gel. Parameters of the network were evaluated from the measured spin-spin relaxation times of the gel swollen in toluene-d 8: about 9 stars are situated between the crosslinks, the non-reacted arms form the dangling chain ends.
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