TU Dortmund, Faculty of Chemistry, Otto-Hahn-Strasse 6, 44227 Dortmund, Germany.
Anal Chem. 2010 Oct 1;82(19):8244-50. doi: 10.1021/ac1013095.
A general approach of size exclusion chromatography (SEC)-NMR is introduced for the determination of the classical molar mass parameters M(W), M(N), and M(P). It can be used for the determination of molar mass distributions of homopolymers and copolymers. The main advantage of SEC-NMR of copolymers is the possibility of detecting each monomer unit simultaneously with NMR as a quantitative concentration detector. Therefore, it is possible to provide the chemical compositions of copolymers at any elution volume without calibrations. In this respect, a new method will be presented for getting correct signal quantities of onflow data with sufficient NMR sensitivities. As the consequence, the chemical composition of copolymers can be correctly quantified under typical chromatographic conditions with respect to sample concentration and flow rate. Finally, the molar mass calibrations of the copolymers can be easily adjusted according to their chemical compositions. The methods were applied to polystyrene-b-poly(methyl methacrylate) block copolymers of different molar masses. The results of the molar mass distributions and the chemical composition distributions obtained by SEC-NMR are in very good agreement with the complex SEC multidetector analysis.
本文介绍了尺寸排阻色谱（SEC）-NMR 用于测定经典的摩尔质量参数 M(W)、M(N) 和 M(P)的一般方法。它可用于测定均聚物和共聚物的摩尔质量分布。共聚物 SEC-NMR 的主要优点是可以同时使用 NMR 作为定量浓度检测器检测每个单体单元。因此，无需校准即可在任何洗脱体积下提供共聚物的化学组成。在这方面，将提出一种新的方法，以在具有足够 NMR 灵敏度的情况下获得正确的流动数据信号量。因此，在典型的色谱条件下，共聚物的化学组成可以根据样品浓度和流速进行正确的定量。最后，可以根据共聚物的化学组成轻松调整其摩尔质量校准。这些方法已应用于不同摩尔质量的聚苯乙烯-b-聚（甲基丙烯酸甲酯）嵌段共聚物。通过 SEC-NMR 获得的摩尔质量分布和化学组成分布的结果与复杂的 SEC 多检测器分析非常吻合。
