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Keywords:

  • crystallinity;
  • hydrogen bonding;
  • microphase separation;
  • water resistance;
  • waterborne poly(urethane urea);
  • well-defined hard segments

Abstract

A series of polyester-based poly(urethane urea) (PUU) aqueous dispersions with well-defined hard segments were prepared from polyester polyol, 4,4′-diphenylmethane diisocyanate, dimethylolpropionic acid, 1,4-butanediol, isophorone diisocyanate, and ethylenediamine. These anionic-type aqueous dispersions had good dispersity in water and were stable at the ambient temperature for more than 1 year. For these aqueous dispersions, the particle size decreased as the hard-segment content increased, and the polydispersity index was very narrow (<1.10). Films prepared with the PUU aqueous dispersions exhibited excellent waterproof performance: the amount of water absorption was as low as 5.0 wt %, and the contact angle of water on the surface of this kind of film was as high as 103° (this led to a hydrophobic surface). The water-resistant property of these waterborne PUU films could be well correlated with some crystallites and ordered structures of the well-defined hard segments formed by hydrogen bonding between the urethane/urethane groups and urethane/ester groups, as well as the degree of microphase separation between the hard and soft segments in the PUU systems. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2606–2614, 2005