Polycarbonates from the Polyhydroxy Natural Product Quinic Acid
Polycarbonates from the Polyhydroxy Natural Product Quinic Acid
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DOI：
10.1021/bm2003048
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发表时间：
2011-07-01
影响因子：
6.2
通讯作者：
Wooley, Karen L.
中科院分区：
文献类型：
--
作者：
Besset, Celine J.;Lonnecker, Alexander T.;Wooley, Karen L.
针对基于奎尼酸的生物源聚碳酸酯，开发了用于制备源自天然多羟基单体重复单元的聚碳酸酯的策略。设计并合成了具有区域选择性的叔丁基二甲基硅氧基（TBS）保护的奎尼酸1，4-和1，5-二醇单体，并优化了它们与氯甲酸三氯甲酯原位生成的光气的共聚反应，得到了保护的聚1，4-奎尼酸碳酸酯和聚1，5-奎尼酸碳酸酯。分子量达到约。7.6 kDa，对应于ca. 24，多分散性范围为2.0 - 3.5，如通过SEC使用四氢呋喃作为洗脱剂和聚苯乙烯校准标准物测量的。部分由于双环主链的存在，每种区域异构聚（奎尼酸碳酸酯）表现出相对高的玻璃化转变温度，聚（1，4-奎尼酸碳酸酯）为209 ℃，聚（1，5-奎尼酸碳酸酯）为229 ℃。在温和条件下研究了TBS保护基团的去除，以实现对涉及聚合物降解的潜在竞争反应的控制，所述竞争反应可以包括重复单元内的内酯、碳酸酯键或重复单元之间的两者的裂解。在没有一定程度的聚合物降解的情况下，不能实现完全脱保护。的单体的区域化学表现出显着的影响，在脱保护过程中的反应性，也对热性能，与1，4-区域异构体相比，与1，5-区域异构体聚合物具有较低的反应性，并给出较高的T-g值。在部分除去TBS-保护基后，每种区域异构体的T-g经历10-20 ℃的增加。随着脱保护程度的增加，溶解度降低。最终，在长的脱保护反应时间下，溶解度增加并且T-g降低，因为聚合物的显著降解。
Strategies for the preparation of polycarbonates, derived from natural polyhydroxy monomeric repeat units, were developed for biosourced polycarbonates based on quinic acid. The design and synthesis of regioselectively tert-butyldhnethyl-silyloxy (TBS)-protected 1,4- and 1,5-diol monomers of quinic acid were followed by optimization of their copolymerizations with phosgene, generated in situ from trichloromethyl chloroformate, to yield protected poly(1,4-quinic acid carbonate) and poly(1,5-quinic acid carbonate). The molecular weights reached ca. 7.6 kDa, corresponding to degrees of polymerization of ca. 24, with polydispersities ranging from 2.0 to 3.5, as measured by SEC using tetrahydrofuran as the eluent and with polystyrene calibration standards. Partially because of the presence of the bicyclic backbone, each regioisomeric poly(quinic acid carbonate) exhibited relatively high glass-transition temperatures, 209 degrees C for poly(1,4-quinic acid carbonate) and 229 degrees C for poly(1,5-quinic acid carbonate). Removal of the TBS-protecting groups was studied under mild conditions to achieve control over potential competing reactions involving polymer degradation, which could include cleavage of lactones within the repeat units, carbonate linkages, or both between the repeat units. Full deprotection was not achieved without some degree of polymer degradation. The regiochemistry of the monomer showed significant impact on the reactivity during deprotection and also on the thermal properties, with the 1,5-regioisomeric polymer having lower reactivity and giving higher T-g values, in comparison with the 1,4-regioisomer. Each regioisomer underwent a 10-20 degrees C increase in T-g upon partial removal of the TBS-protecting groups. As the extent of deprotection increased, the solubility decreased. Ultimately, at long deprotection reaction times, the solubility increased and the T-g decreased because of significant degradation of the polymers.