The present invention is a copolymer of a monomer mixture including about 25 to about 80 parts by mass of an alkyl (meth)acrylate, approximately 15 to approximately 50 parts by mass of a hydroxyl group-containing monomer, and approximately 5 to approximately 25 parts by mass of a macromer having a glass transition temperature (Tg) of approximately 50° C. or higher. The copolymer contains substantially no acidic groups.