Organocatalytic Approach to Amphiphilic Comb-Block Copolymers Capable of Stereocomplexation and Self-Assembly

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• 作者：Kazuki Fukushima ; Russell C. Pratt ; Fredrik Nederberg ; Jeremy P. K. Tan ; Yi Yan Yang ; Robert M. Waymouth ; James L. Hedrick
• 刊名：Biomacromolecules
• 出版年：2008
• 出版时间：November 10, 2008
• 年：2008
• 卷：9
• 期：11
• 页码：3051-3056
• 全文大小：272K
• 年卷期：v.9,no.11(November 10, 2008)
• ISSN：1526-4602

文摘

Biocompatible amphiphilic block copolymers comprised of poly(ethylene glycol) (PEG) as the hydrophilic component and a poly(methylcarboxytrimethylene carbonate) (PMTC) as a hydrophobic backbone having either poly(class="smallcaps">l-lactide) (class="smallcaps">l-PLA) or poly(class="smallcaps">d-lactide) (class="smallcaps">d-PLA) branches were prepared by organocatalytic ring-opening polymerization (ROP). The polycarbonate backbone was prepared by copolymerization of two different MTC-type monomers (MTCs) including a tetrahydropyranyloxy protected hydroxyl group, a masked initiator for a subsequent ROP step. Interestingly, the organic catalyst used in the ROP of MTCs was also effective for acetylation of the hydroxyl end-groups by the addition of acetic anhydride added after polymerization. Acidic deprotection of the tetrahydropyranyloxy (THP) protecting group on the carbonate chain generated hydroxyl functional groups that served as initiators for the ROP of either class="smallcaps">d- or class="smallcaps">l-lactide. Comb-shaped block copolymers of predictable molecular weights and narrow polydispersities (∼1.3) were prepared with up to 8-PLA branches. Mixtures of the class="smallcaps">d- and class="smallcaps">l-lactide based copolymers were studied to understand the effect of noncovalent interactions or stereocomplexation on the properties.