K. Ohno, Y. Tsujii, T. Miyamoto
Jan 31, 1998
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Journal
Macromolecules
Abstract
This is the first report of the synthesis of a well-defined glycopolymer by free radical polymerization. N-(p-vinylbenzyl)-[O-β-d-galactopyranosyl-(1→4)]-d-gluconamide (VLA), a styrene derivative with an oligosaccharide moiety, was polymerized in N,N-dimethylformamide solution at 90 °C by the nitroxide-mediated free radical polymerization technique. Acetylated VLA gave polymers with a molecular weight from about 2000 to 40 000, an Mw/Mn ratio of about 1.1 in all cases, and a conversion of up to about 90%, where Mw and Mn are the weight- and number-average molecular weights. Indispensable for this success were (1) the use of di-tert-butyl nitroxide (DBN) rather than other nitroxides such as TEMPO, (2) the acetylation of VLA, and (3) the use of a radical initiator DCP (dicumyl peroxide) as an accelerator. DBN provided a well-controlled polymerization of VLA at 90 °C (VLA becomes unstable at higher temperatures, e.g., >120 °C). The acetylation effectively prevented the chain transfer that leads to dead polym...