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Hydrogel compositions demonstrating phase separation on contact with aqueous media

  • US 9,089,481 B2
  • Filed: 09/06/2013
  • Issued: 07/28/2015
  • Est. Priority Date: 05/01/2001
  • Status: Expired due to Fees
First Claim
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1. A phase separating, film-forming composition comprising:

  • a water-swellable acrylate-based polymer, said polymer being insoluble in water at a pH less than about 5.5;

    a blend of a poly(N-vinyl lactam) homopolymer and a complementary oligomer capable of hydrogen bonding to the poly(N-vinyl lactam) homopolymer;

    a water-swellable cellulose ester polymer, that is insoluble in water at all pH values; and

    an optional active agent,wherein upon exposure to an aqueous environment at a pH of from about 6-8, the composition undergoes a phase separation wherein the water-swellable cellulose ester polymer forms a film over the remainder of the composition comprising the water-swellable acrylate-based polymer or, the blend of the poly(N-vinyl lactam) homopolymer and complementary oligomer and optional active agent; and

    wherein the weight ratio of the acrylate-based polymer to the cellulose ester polymer is within a range of about 1.5;

    1 to 2;

    1.

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