Lactide polymerization co-initiated by carbohydrate esters and pyranoses

The polymerization of [S]-lactide was accomplished using an initiating system comprising an alkyl zinc complex and a series of well defined carbohydrate co-initiators derived from D-glucose, D-xylose, and 2-deoxy-D-ribose. The monosaccharide co-initiators were aldonate esters and pyranoses, they were all prepared in high yield and had only a single alcohol co-initiating group; the remaining carbohydrate hydroxyl functionalities were protected as acetyl, benzyl ether and isopropylidene acetal groups. The polymerizations were all well controlled, illustrated by the linear increase in poly(S-lactide) M. with percentage conversion of lactide, the increase in poly(S-lactide) Mu with [lactide](0)-[lactide](t)/[co-initiator] and the narrow polydispersity indices of the polylactides. Thus, the novel initiating systems were used to produce poly(S-lactides) end functionalized with a variety of different aldonate ester and pyranose groups and with degrees of polymerization from 10 to 250. The polyesters were fully characterized, including by NMR spectroscopy, size exclusion chromatography (SEC), matrix-assisted laser deposorption/ionization (MALDI) mass spectrometry and by static water contact angle measurements. (c) 2008 Wiley Periodicals, Inc.