Macromonomer for preparation of a degradable hydrogel

A macromonomer for preparation of a degradable hydrogel, the macromonomer formed by the process of reacting:

• a) a hydrophilic polymer including at least two hydroxyl groups, the hydrophilic polymer being selected from the group consisting of polyethylene glycol, di- and tri-block copolymers of polyethylene glycol and polypropylene glycol, and a combination thereof with;
• b) a difunctional monomer to form an intermediate, the difunctional monomer comprising an acid halide group, an alkyl halide group, and a spacer that is a straight or branched alkyl group, wherein the acid halide group of the difunctional monomer reacts with one of the hydroxyl groups of the hydrophilic polymer such that the intermediate has a first ester bond on a backbone of the intermediate, the oxygen of the first ester bond being along the backbone of the intermediate and being between the hydrophilic polymer residue and the carbonyl group of the first ester bond, the intermediate including the alkyl halide group as a terminal group;
• and
• reacting the intermediate with
• c) a metallic salt of a vinyl acid monomer to form the macromonomer, wherein the terminal alkyl halide group of the intermediate reacts with the acid group of the vinyl acid monomer such that the macromonomer has a second ester bond on the backbone of the macromonomer, the oxygen of the second ester bond being along the backbone of the macromonomer and being between the alkyl group of the alkyl halide group and the carbonyl group of the second ester bond, the macromonomer having a terminal vinyl group;
• the macromonomer comprising the structure
• wherein R1 is the residue of the hydrophilic polymer, and
• R2 is the spacer that is a straight chain or branched alkyl group.