采用Zwitterionic聚合,产生高分子量循环多碳酸
Hayley A Brown1, Young A Chang, Robert M Waymouth
1Department of Chemistry Stanford University , Stanford, California 94305, United States.
Journal of the American Chemical Society
|December 7, 2013
概括
N-异环碳通过环开放有效地聚合了2,2,5,5-四甲基-2,5-二甲基-1-氧cyclopentane (TMOSC). 这种方法在室温下快速产生高分子量循环聚碳素.
科学领域:
- 聚合物化学 聚合物化学
- 有机化学 有机化学
- 催化剂是一种催化剂.
背景情况:
- 环开聚合 (ROP) 是合成聚合物的关键方法.
- N-异环碳 (NHCs) 是各种有机转换的有力核友和催化剂.
- 循环素是先进材料的多功能构建模块.
研究的目的:
- 为了研究NHC介导的循环素单体,2,2,5,5-四甲基-2,5-disila-1-oxacyclopentane (TMOSC) 的zwitterionic环开放聚合.
- 探索NHC核性对聚合动力学和聚合物特性的影响.
- 描述由此产生的多碳素和阐明聚合机制.
主要方法:
- 采用两种不同的NHC催化剂 (IMes和一种更为核性类似物) 的TMOSC的Zwitterionic环开聚合.
- 使用凝浸透染色学 (GPC) 和矩阵辅助激光脱落/电离-飞行质谱时间 (MALDI-TOF MS) 进行聚合物的表征.
- 稀释溶液粘度研究和密度功能理论 (DFT) 计算以确定聚合物结构和反应机制.
主要成果:
- TMOSC的NHC介导的ROP在室温下迅速实现了高分子量聚碳素 (Mn高达940,000Da).
- 聚合率和分子重量受到NHC催化剂核友性的显著影响.
- 由此产生的聚合物主要是循环的,由粘度和质谱数据证实.
- DFT计算支持聚合途径中的zwitterionic和中性循环中间体.
结论:
- NHC催化提供了一条有效的途径,用于从TMOSC中控制合成高分子量循环多糖素.
- 选择NHC催化剂对于控制聚合动力学和实现高分子量至关重要.
- 聚合物的主要循环性质为它们在先进材料应用中的使用开辟了道路.
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