Patent ID: 8920841

Claim:
A polymer system useful for in vivo delivery of a therapeutic agent, wherein the polymer system comprises at least one transition co-monomer in an amount of about 50-99.5% by weight that renders the polymer system capable of reversible stimuli induced transition from a liquid to a gel, and an acrylated lactone-containing co-monomer in an amount of about 0.5-15% by weight, an amine-reactive co-monomer in an amount of up to about 15% by weight and a hydrophilic co-monomer in an amount up to about 15% by weight, wherein the transition co-monomer, amine-reactive co-monomer, hydrophilic co-monomer and the acrylated lactone-containing co-monomer are polymerized within the polymer system and wherein the lactone ring of the acrylated lactone-containing co-monomer exists as a side chain within the polymer system which is subject to hydrolytic ring opening but remains attached to the polymer system to transition the polymer system from a gel to a liquid under physiological conditions.