Johnson Jeremiah A, Lewis Danielle R, Díaz David D, Finn M G, Koberstein Jeffrey T, Turro Nicholas J
Department of Chemistry, Columbia University, 3000 Broadway, MC3157, New York, New York 10027, USA.
J Am Chem Soc. 2006 May 24;128(20):6564-5. doi: 10.1021/ja0612910.
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 first tert-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.
采用一种简单的方案来制备首个丙烯酸叔丁酯模型网络，该方案包括从双官能引发剂进行原子转移自由基聚合（ATRP）、将所得遥爪聚合物的溴端基转化为叠氮化物，以及通过铜催化的叠氮化物-炔烃环加成反应使这种叠氮基遥爪大分子单体与多乙炔官能化的小分子交联。这种通用方案适用范围广泛，能够从任何可通过ATRP聚合的单体合成具有确定孔径的模型网络。将烯烃部分引入ATRP引发剂可通过臭氧分解使材料降解，根据在母体网络中使用的交联剂不同，生成带有三个或四个臂的星形聚合物产物。臭氧分解产物的尺寸排阻色谱法证实了母体网络的孔径，并深入了解了未反应官能团的数量。发现源自三官能炔烃的模型网络比源自四官能炔烃的模型网络交联更完全，这可能是由于前一种体系中的空间位阻较小。
