Several poly(alkyl methacrylate-b-t-butyl methacrylate) diblock copolymers were synthesized by group transfer polymerization. The molecular weight of poly(t-butyl methacrylate) segments and the composition of the resulting block copolymers were controlled by the monomer feed ratios and mole ratios of monomer to initiator. The poly(t-butyl methacrylate) block was quantitatively hydrolyzed to poly(methacrylic acid) block by refluxing with a catalytic amount of p-toluenesulfonic acid in dioxane at $100^{circ}C$ for 12 hrs. The thermogravimetric analysis of poly(alkyl methacrylate-b-t-butyl methacrylate) exhibited the lose of isobutylene and subsequent anhydride formation in the range of $205-300^{circ}C$.