低分子量聚酯的13C NMR研究

本文对由己二酸、邻苯二甲酸、乙二醇、二甘醇和1、4-丁二醇形成的几种不同组成和分子量的低分子量聚酯进行了¹³C NMR研究。应用模型化合物^1],经验公式^2]和实验方法相结合,对5种不同组成和分子量的低分子量聚酯的¹³C NMR图谱进行了全归属;利用PRFT和反门控去偶技术测定了有关碳原子的自旋晶格弛豫时间(T₁)范围和NOE因子;在此基础上选择了最佳实验条件,测得了各样品的数均分子量,所得结果与端基分析法测得的结果非常接近。表明¹³C NMR不仅可以用于结构分析,选择合适的条件还可得到令人满意的定量结果。

THE ~(13)C NMR STUDY FOR LOW MOLECULAR WEIGHT POLYESTERS

A 13C NMR study of a series of low molecular weight polyesters derived from ethylene glycol, diethylene glycol, 1, 4-butanediol.adipic acid and phthalic acid is reported.13C resonances in the five samples were assigned by model compound study, empirical rules and experimental methods. The spin-lattice relaxation time (T1) range and nuclear overhauser enhancement(NOE) factor were measured with PRFT and inverse gated decoupling technology. Based on this information, the optimal quantitative measurement conditions were selected and the number-average molecular weight for each sample was obtained. The results are in agreement with those from terminal group analysis. It was shown that 13C NMR is not only suitable for structure determination, but also suitable for quantitative measurement under certain condition.