【摘要】 研究了苯乙炔在1.5,6和10小时的热聚合过程中温度对聚合物分子量的影响。所得结果表明,在150—500°的温度范围内,随着聚合温度的增高,聚合物的分子量都是逐渐降低,表明在高温时聚合物有裂解现象发生。红外光谱显示,400°所得聚合物的光谱吸收峯较之200°聚合物的为小,500°聚合物则出现无明显吸收峯的连续吸收,并且背景升高(“背景效应”)。聚合物的碳氢含量此同样随着聚合温度的升高而增大。这些结果,以及300°以上聚合物在溶液中显示明显的萤光等,被认为是表明聚苯乙炔在高温时发生结构改变,除裂解成小分子外,可能还有环化、脱氢、芳构化等发生,从而由链状结构变为稠环结构乃至三维共轭结构。 聚合物的电子自旋共振测试表明,聚苯乙炔的自由基浓度随下列顺序递增: 300°聚合物<400°聚合物<500°聚合物。更多还原

【Abstract】 A study of the effect of temperature on the molecular weight of polyphenyl-acetylene in the thermal polymerization of phenylacetylene for 1.5, 6 and 10 hours has been undertaken. The results obtained showed, in the temperature range between 150° and 500°, the average molecular weight of the polymer gradually decreased as the temperature increased, indicating that degradation of the polymer occurred at higher temperature. The infrared spectra showed that the absorption bands of the polymer obtained at 400° were smaller than that of the polymer obtained at 200°, while the polymer obtained at 500° showed no noticeable absorption bands but rather a continuous absorption at an enhanced level ("background effect"). The ratio of carbon and hydrogen content of the polymers also increased as the temperature of polymerization was raised. These results, in conjunction with the fact that the polymers obtained above 300° showed a distinct fluorescence in solution, are taken to indicate that polyphenylacetylene underwent structural changes at higher temperature and there was, besides degradation to small fragments, probably also cyclization, dehydrogenation, and aromatization, thus converting the chain structure to condensed ring system and thence to three dimensional conjugated system.The determination of the electron spin resonance of the polymers showed that the concentration of free radicals in the polyphenylacetylene increased in the following order: 300° polymer < 400° polymer < 500° polymer.更多还原