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我们发现芳香叔胺是丙烯腈聚合极有效的光引发剂。芳香叔胺苯环上氢被正性基取代时,引发能力增加,被负性基取代时,引发能力下降。下列胺的活性次序是:N,N-二甲基对甲苯胺(DMT)>N,N-二羟乙基对甲苯胺(DHET)>N,N-二甲基苯胺(DMA)>N,N-二甲胺基苯甲醛(DMB)>N,N-二甲基对硝基苯胺(DNA)。芳香叔胺引发丙烯腈光聚合属自由基机构,聚合速度与叔胺浓度的0.66次方成正比。在叔胺浓度为10~(-2)—10~(-4)M范围内,聚合物平均聚合度的倒数与叔胺浓度的0.5次方成正比。初步认为在紫外光激发下,芳香叔胺与丙烯腈分子生成激发态电子转移络合物,再分解产生自由基,引发丙烯腈聚合。
We found that aromatic tertiary amines are very effective photoinitiators for the polymerization of acrylonitrile. Aromatic tertiary amine benzene ring hydrogen is replaced by the positive group, the priming capacity increased by the negative group, the priming capacity decreased. The order of activities for the following amines is: DMET> DHET> DMA> N, N-dimethylanilinium (DMA) N-dimethylaminobenzaldehyde (DMB)> N, N-dimethyl-p-nitroaniline (DNA). Aromatic tertiary amine initiated acrylonitrile photopolymerization of free radical mechanism, the polymerization rate is proportional to the tertiary amine concentration of 0.66. In the range of 10 ~ (-2) -10 ~ (-4) M, the reciprocal of the average polymerization degree of the polymer is proportional to the 0.5th power of the tertiary amine concentration. It is preliminarily believed that under the excitation of UV light, the aromatic tertiary amine and acrylonitrile molecules generate excited state electron transfer complexes, which decompose to generate free radicals to initiate the polymerization of acrylonitrile.