Kinetics of surface-initiated atom transfer radical polymerization of acrylamide on silica
Kinetics of surface-initiated atom transfer radical polymerization of acrylamide on silica
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DOI：
10.1021/ma011313x
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发表时间：
2002-04-09
期刊：
影响因子：
5.5
通讯作者：
Wirth, MJ
中科院分区：
文献类型：
--
作者：
Xiao, DQ;Wirth, MJ
采用CuCl/CuCl_2/三（2-二甲氨基乙基）胺催化体系，在室温下实现了丙烯酰胺的表面原子转移自由基聚合（ATRP）。聚丙烯酰胺膜的厚度与单体浓度成正比，而与反应时间不成正比。这一行为定性类似于使用CuCl/联吡啶催化体系的丙烯酰胺的表面ATRP，其需要130 degreesC用于引发。动力学研究表明，在室温下，链增长率和链终止率都较高，尽管高得多的浓度的Cu（II），以减少在室温下的自由基人口。XPS表明，在表面的氯浓度下降，随着聚合反应的进展，表明终止是由自由基组合。对于室温下在硅胶上的聚合，微量分析表明，在聚合过程中损失了一半的氯。仅用铜催化剂平衡表面结合的引发剂表明，大部分氯损失是由于引发剂自由基的结合。
Surface-initiated atom transfer radical polymerization (ATRP) of acrylamide is achieved on silica at room temperature by using a catalytic system of CuCl/CuCl2/tris(2-dimethylaminoethyl)amine. The thickness of the polyacrylamide film is proportional to the monomer concentration but not to reaction time. This behavior is qualitatively similar to that for surface ATRP of acrylamide using a CuCl/bipyridine catalytic system, which required 130 degreesC for initiation. A kinetic study shows that, at room temperature, both the rate for chain propagation and the rate of chain termination are higher, despite a much higher concentration of Cu(II) to reduce the radical population at room temperature. XPS shows that the concentration of chlorine at the surface drops as the polymerization reaction progresses, indicating that termination is caused by radical combination. For polymerization on silica gel at room temperature, microanalysis shows that half of the chlorine is lost during polymerization. Equilibration of the surface-bound initiator with only the copper catalyst shows that most of the chlorine loss is due to the combination of initiator radicals.