摘要
通过调整溶液浓度和测试温度等测试参数,与文献[1]比较我们获得了无规聚丙烯腈(PAN)和部分全同PAN样品更高分辨率的13C核磁共振谱.合理归属了次甲基碳的五单元组(mmmm、mmmr和rmmr)、腈基碳与次甲基碳的七单元组(mmmmmm、mmmmmr和rmmmmr)各特征峰.无规PAN样品服从伯努利统计模型.一级马尔科夫和二级马尔科夫统计模型分别被用于定量计算部分全同PAN样品的五单元组和七单元组的立构分布.计算了不同立构规整度样品的"全同单元段"和"间同单元段"平均长度,从另一方面证实了上述的七单元组归属的正确性.
High-resolution 13C NMR spectra of atactic polyacrylonitrile （PAN） and isotactic-rich PAN were obtained under optimized solution concentration and experimental temperature. Assignments of nitrile carbon atoms with heptads were obtained and shown to be different from previously reported. The methenyl carbon atoms with pentads and heptads were assigned, respectively. It was shown that the atactic PAN obeys Bernoullian statistics. First-order and second-order Markov statistics were applied to calculate the content of the n-ads in isotactic-rich PAN. The number-average lengths of the isotactic and syndiotactic sequences calculated by ＂block＂ statistics confirmed the assignments of the heptads by 13C NMR spectroscopy.
出处
《波谱学杂志》
CAS
CSCD
北大核心
2008年第2期176-183,共8页
Chinese Journal of Magnetic Resonance
基金
国家自然科学基金重点项目资助(50333060)
