Organocatalyzed ROP of a Glucopyranoside Derived Five-Membered Cyclic Carbonate
Organocatalyzed ROP of a Glucopyranoside Derived Five-Membered Cyclic Carbonate
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DOI：
10.1021/acs.macromol.7b01785
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发表时间：
2018-03-13
期刊：
影响因子：
5.5
通讯作者：
Wooley, Karen L.
中科院分区：
文献类型：
--
作者：
Felder, Simcha E.;Redding, McKenna J.;Wooley, Karen L.
基于其广泛的生物利用度、高化学官能度和立体化学多样性，异丙交酯是用于开发新的合成聚合物的有吸引力的起始材料。利用已建立的羰基化方法从市售的D-吡喃葡萄糖苷衍生物以高产率（>95%）合成5元环状碳酸酯单体4，6-O-亚苄基-2，3-O-羰基-α-D-吡喃葡萄糖苷（MBGC）。该单体进行开环聚合（ROP）的能力与一系列的有机催化剂，而不是以前报道的阴离子引发剂，进行了研究。这些新的条件被开发以拓宽聚合中的官能团耐受性，并实现对聚合物的最终性质的更好控制。最有前途的催化剂检查，1，5，7-三氮杂双环[4.4.0]癸-5-烯（TBD），用于动力学研究，以确认良好控制的性质的ROP。优化的条件，然后成功地应用于不同分子量的聚合物的合成。通过去除亚苄基缩醛保护基团以释放水溶性聚（葡萄糖碳酸酯），然后添加乙酰基以便于表征研究，完成了两个聚合后修饰。进行MALDI-TOF MS分析以进一步探测聚合和脱保护的化学。通过该系列聚合物实现了宽范围的热分解温度（233-347摄氏度）、玻璃化转变温度（87-233摄氏度）和水接触角（38-128度）。还检查了这些聚合物的水解降解性，证明了基于所用的酸性与碱性条件的不同降解机制。因此，该单一单体成功地用于直接合成具有基于分子量和重复单元组成的可调性质的聚合物体系。
Saccharides, based on their wide bioavailability, high chemical functionality and stereochemical diversity, are attractive starting materials for the development of new synthetic polymers. Established carbonylation methodologies were used to synthesize a 5-membered cyclic carbonate monomer, 4,6-O-benzylidene-2,3-O-carbonyl-alpha-D-glucopyranoside (MBGC), in high yield (>95%) from a commercially available D-glucopyranoside derivative. The ability of this monomer to undergo ring opening polymerization (ROP) with a range of organocatalysts, rather than the previously reported anionic initiators, was investigated. These new conditions were developed to widen the functional group tolerance in the polymerization, and achieve better control over the final properties of the polymers. The most promising of the catalysts examined, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), was used in a kinetic study to confirm the well-controlled nature of the ROP. Optimized conditions were then successfully applied to the synthesis of polymers of different molecular weights. Two post-polymerization modifications were completed via the removal of the benzylidene acetal protecting group to release a water-soluble poly(glucose carbonate), and then addition of acetyl groups to facilitate characterization studies. MALDI-TOF MS analysis was performed to further probe the chemistry of the polymerization and deprotection. A wide range of thermal decomposition temperatures (233-347 degrees C), glass transition temperatures (87-233 degrees C), and water contact angles (38-128 degrees) was achieved by this series of polymers. The hydrolytic degradability of these polymers was also examined, demonstrating differing degradation mechanisms based on the acidic vs. basic conditions used. Consequently, this single monomer was successfully employed in the straightforward synthesis of a polymeric system with tunable properties based on the molecular weight and repeat unit composition.