The present invention is directed to a crosslinked or non-crosslinked polymer particle, wherein the crosslinked polymer particle comprises a copolymer of poly(alklyene glycol-graft-lactate) that is crosslinked by at least one hydrolysable monomer. Another embodiment of the present invention is a polymer particle comprising a crosslinked polymer particle that is a product of starting materials comprising (a) a hydrophilic monomer, (b) a hydrophobic monomer, and (c) a hydrolysable crosslinking agent. Another embodiment of the present invention is a polymer particle comprising, a crosslinked copolymer comprises structures represented by Formulas (I), (II), and (III), where Formulas (I), (II) and (III) are defined in the specification. Yet other embodiments of the present invention include a method of preparing a methacrylate terminated macromonomer, a method of preparing a crosslinking agent, and a method of preparing a therapeutic agent loaded nanosphere by dispersion polymerization.