Comparison of Molar Mass Determination of Poly(dimethylsiloxanes) by Size Exclusion Chromatography and High-Resolution Polymer High Performance Liquid Chromatography Based on a Sawtooth Gradient

Polysiloxanes are used in a wide range of application fields, and extensive research is currently done to enhance product quality and performance. Therefore, more sophisticated analysis methods are necessary to monitor and support the polymer product optimization. Based on different modes in polymer liquid chromatography, heart-cut polymer HPLC is one powerful analytical approach. Due to different distributions within polymer samples, separations according to chemical heterogeneities, molecular architecture, or molar mass differences are possible. With the recently introduced sawtooth gradient protocol a possibility for determining the polymer (micro-)structure on an analytical scale has been developed. Hence, the effect of various stationary phases with different particle based material and chemical modifications was investigated in the context of the separation of linear poly(dimethylsiloxane) in a molar mass range from 1000 g·mol–1 to 300,000 g·mol–1. The resulting chromatograms allowed a direct correlation between HPLC retention times and molar masses corresponding to separated peaks. Consequently, a detailed analysis of differences in the polymer structure, e.g., fingerprint analysis, is possible. This special technique could be used in the context of quality control to ensure the product stability of polymer samples.