Ring opening copolymerization of ε-caprolactone, γ-(triethylsilyloxy)-ε-caprolactone and γ-ethylene ketal-ε-caprolactone:: a route to hetero-graft copolyesters

epsilon-Caprolactone (epsilon-CL) has been copolymerized with two precursors of gamma-hydroxy-epsilon-CL, i.e., gamma-ethylene ketal-epsilon-caprolactone (TOSUO) and gamma-(triethylsilytoxy)-epsilon-caprolactone (TeSCL). The triethylsilyloxy pendant groups can be selectively deprotected into hydroxyl groups followed by the deprotection of the acetal substituents. Each series of hydroxyl groups can be used to initiate the polymerization of cyclic monomers so leading to hetero-graft copolyesters with, for instance, poly-epsilon-CL and polylactide grafts.