Magnetic field effect on photocrosslinking reaction of directly excited azidomethylated polystyrene
Magnetic field effect on photocrosslinking reaction of directly excited azidomethylated polystyrene
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磁场对直接激发叠氮甲基化聚苯乙烯光交联反应的影响
DOI：
10.1002/app.1990.070410919
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发表时间：
1990
影响因子：
3
通讯作者：
N. Uchino
中科院分区：
文献类型：
--
作者：
H. Morita;N. Uchino
测量了聚苯乙烯-乙烯基苯并叠氮共聚物(AZMS)薄膜在低压汞灯照射和外加磁场作用下的凝胶分数。在0.089 T的磁场作用下，AZMS的凝胶含量降低，光交联率降低20%，而敏化光交联剂的光交联率随磁场的增加而提高，光交联率降低≈为20%。根据直接激发AZMS的光交联机理，得出结论：AZMS单重态激发产生的单重态氮从AZMS聚合物中抽出一个氢原子形成单重态自由基对，磁场降低了自由基对的单重态-三重态体系交叉率。
Gel fractions of thin films of poly(styrene-co-vinylbenzyl azide) (AZMS) irradiated with a low pressure mercury lamp were measured in the absence and in the presence of an external magnetic field. By the application of a magnetic field of 0.089 T, the gel fraction of AZMS decreases, and the efficiency of photocrosslink formation decreases by ≈ 20%, in contrast to the case of sensitized photocrosslinking of AZMS where the efficiency increases by the application of a magnetic field. Based on the photocrosslinking mechanism of directly excited AZMS, it is concluded that the singlet nitrene which is produced from the singlet excited AZMS abstracts a hydrogen atom from the AZMS polymer to form the singlet radical pair, and that the magnetic field decreases the singlet–triplet intersystem crossing rate of the radical pair.