Dispenser constructed with semipermeable polymer-hydrophilic polymer wall

Claim 1

A dispenser comprising: an outer wall formed of a semi-permeable polymer onto which is grafted a hydrophilic polymer, the semi-permeable polymer comprising the general formula: ##STR3## wherein R is a member selected from the group consisting of hydrogen, alkyl of 1 to 7 carbon atoms, acetyl, propionyl, butyryl, valeryl, pivaloyl, and the hydrophilic polymer comprising the general formula: ##STR4## wherein R 1 and R 3 are a member selected from the group consisting of hydrogen, alkyl of 1 to 7 carbon atoms, and alkenyl of 2 to 4 carbon atoms, R 2 and R 4 are a member selected from the group consisting of hydroxyl, --O-alkali metal and NH 2 , a is 1 to 4, b is 0 to 4, p is 30 to 100,000, m is 0 to 5000, n is 0 to 5000 with the total of m plus n at least 500, and at least one of said R is the hydrophilic member, which wall surrounds and defines an internal space; a container for storing a member selected from the group consisting of a fluid and a beneficial agent in the internal space, the container formed of an elastomeric polymer that is changeable from a storing capacity to a substantially emptied capacity over time; an outlet passageway in the wall communicating with the container and the exterior of the dispenser for dispensing the stored member over time; and wherein when the dispenser is in operation in the environment of use, the dispenser releases the beneficial member in response to the wall admitting and absorbing fluid from the environment and expanding, thereby exerting pressure on the container which collapses under the pressure and ejects the member through the passageway from the dispenser over time.