Membrane modified hydrogels
AssigneeCiba-Geigy Corporation
InventorsKarl F. Mueller, Sonia J. Heiber
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Abstract
Non-uniform water-insoluble interpenetrating polymer blend compositions comprising a first permeable water swellable polymer substrate interpenetrated in a gradient substantially normal to the substrate surface by a second less permeable condensation polymer to form a diffusion rate controlling membrane therein. Such compositions are useful as polymers with reduced permeabilities for water and organic solvents and therefore for the controlled delivery of active ingredients such as fragrances and bio-affecting agents into air or aqueous environments, or in membrane separation processes.
Claims20
A non-uniform substantially water-insoluble interpenetrating polymer blend composition comprising a water swellable first polymer substrate interpenetrated in a gradient substantially normal to the substrate surface by a less permeable condensation second polymer to form a diffusion rate controlling membrane therein.
A water actuated diffusion type active agent dispenser including a means for dispensing a dosage of active agent into an aqueous fluid environment, comprising a bead of a substantially water insoluble water swellable first polymer interpenetrated by a diffusion rate controlling membrane parallel to the surface of said bead, said membrane consisting essentially of said first polymer interpenetrated by a less permeable condensation second polymer, said membrane forming an inclosure for said active agent to continuously dispense said agent at a controlled and continuous rate by diffusion across the membrane.
Dependencies are inferred from the claim text.