Abstract
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 °C was used for the copolymerization of [l]-LA with IPPTC. When fLA/fIPPTC was 91/9, the percent yield, Mn, 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 °C, 14 mol % IPPTC) and have higher thermal stabilities and higher glass transition temperatures (69 °C, 100 mol % IPPTC). The liberation of hydroxyl pendant groups by the selective removal of the benzyl ether, the ketal ...
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