Online HPLC–NMR: An Efficient Method for the Analysis of PMMA with Respect to Tacticity
2016-02-18T17:30:00Z (GMT) by
New methods of liquid adsorption chromatography were developed to separate poly(methyl methacrylate) (PMMA) regarding tacticity and molar mass. Gradient and isocratic chromatographic methods were applied to separate the tactic polymers. In particular, the online coupling of HPLC–NMR was used to identify and quantify the microstructural moieties during the chromatographic separation. It was possible to individually follow the elution of the syndiotactic, heterotactic as well as isotactic patterns. Several representative blends of PMMA samples of different tacticities as well as molar masses were well separated and analyzed. The quantification of all tacticities of the HPLC–NMR measurements was performed and the overall compositions were in good agreement with the data on the bulk samples. In addition, SEC–NMR data of predominantly isotactic PMMA show dependences of the tacticity on the molar mass.