The new monomer 1,2-O-isopropylidene-3-benzyloxy-pentofuranose-4,4'-cyclic carbonate (IPPTC) was prepared. IPPTC has both a ketal-protected diol and a benzyl ether-protected hydroxyl. Thus, these two sets of hydroxyl groups can be independently deprotected to give IPPTC repeat units with one, two, or three free hydroxyl groups. Stannous octanoate at 130 degreesC was used for the copolymerization of [L]-LA with IPPTC. When f(LA)/f(IPPTC) was 91/9, the percent yield, M-n, and percent incorporation of IPPTC units were 78%, 77 800 g/mol, and 4 mol %, respectively. By the method of Fineman and Ross, the [L]-LA and IPPTC comonomer reactivity ratios were 8.6 and 0.51, respectively. Relative to poly([L]-LA), incorporation of IPPTC units into [L]-LA/IPPTC copolymers gave products that are lower melting (112 degreesC, 14 mol % IPPTC) and have higher thermal stabilities and higher glass transition temperatures (69 degreesC, 100 mol % IPPTC). The liberation of hydroxyl pendant groups by the selective removal of the benzyl ether, the ketal groups, or both was possible without substantial loss in the product molecular weight. The removal of the protecting groups Of poly([L]-LA-co-4.0 mol % IPPTC) did not change the T-m value (160 degreesC) but did alter the copolymer crystallization kinetics and thermal stability.