Synthesis of degradable model networks via ATRP and click chemistry
Synthesis of degradable model networks via ATRP and click chemistry
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DOI：
10.1021/ja0612910
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发表时间：
2006-05-24
影响因子：
15
通讯作者：
Turro, Nicholas J.
中科院分区：
文献类型：
--
作者：
Johnson, Jeremiah A.;Lewis, Danielle R.;Turro, Nicholas J.
以双官能团引发剂为引发剂，通过原子转移自由基聚合，将遥链聚合物中的溴端基团转化为叠氮化合物，再通过铜催化叠氮化−烯烃环加成反应，使叠氮化−遥螺旋大分子与多个乙炔官能化的小分子发生交联反应，合成了新型的丙烯酸叔丁酯模型网络。这一总体方案范围很广，可以从任何可由ATRP聚合的单体合成具有定义孔径的模型网络。在ATRP引发剂中引入烯烃部分可使材料通过臭氧降解生成具有三个或四个臂的星形聚合物产品，这取决于在母体网络中使用的交联剂。臭氧分解产物的大小排除层析确认了母体网络的孔径大小，并获得了对未反应官能团数量的洞察。由三官能团炔衍生的模型网络被发现比来自四官能团炔的模型网络更完全地交联化，这可能是由于前者体系中的空间位阻较小。
A simple scheme involving atom transfer radical polymerization (ATRP) from a bifunctional initiator, conversion of the bromine end groups of the resulting telechelic polymer to azides, and cross-linking of this azido−telechelic macromonomer with multi-acetylene functionalized small molecules via copper-catalyzed azide−alkyne cycloaddition was employed to prepare the firsttert-butyl acrylate model networks. This general scheme is wide in scope, enabling synthesis of model networks possessing defined pore size from any monomer polymerizable by ATRP. Introduction of an olefin moiety into the ATRP initiator enabled degradation of the materials by ozonolysis to yield star polymer products bearing three or four arms depending on which cross-linker was employed in the parent network. Size-exclusion chromatography of the ozonolysis products confirmed the pore size of the parent network and yielded insight into the number of unreacted functionalities. Model networks derived from a trifunctional alkyne were found to be more completely cross-linked than those derived from a tetrafunctional alkyne, presumably due to less steric hindrance in the former system.