Hydrophilic Polyurethane Compositions

摘要

This disclosure relates to a controlled-release composition containing a water-swellable linear polymer together with an active agent. The water-swellable linear polymer is obtained by reacting together: (a) a polyethylene oxide of number average molecular weight less than or equal to 4000 g/mol; (b) an aliphatic diol; and (c) a difunctional isocyanate. The ratio of components (a) to (b) to (c) is in the range of 0.01-0.1 to 1 to 1.01-1.1 in terms of equivalent weights. The amount of the polyethylene oxide is less than 50 wt % of the polymer. The polymer has a water swelling percentage of 20-100%.