Asymmetrical Flow Field-Flow Fractionation and Multiangle Light Scattering for Molar Mass Analysis of Polysaccharide Derivatives
Sammanfattning: Molar mass and molar mass distribution of polymers are parameters of fundamental importance as they influence the performance of the polymer in applications. Polysaccharide derivatives are a class of polymers that have attracted significant scientific and commercial interest as they can be manufactured from a wide range of abundant sources in nature and thereby often are both cheap and biocompatible. However, the molar mass analysis of such derivatives is not always easy with commonly used analytical techniques mainly due to their large size. One technique that has shown its applicability to molar mass analysis of very large polymers, among them polysaccharide derivatives, is the combination of field-flow fractionation (FFF) with multiangle light scattering (MALS). This thesis describes the further evaluation and development of FFF-MALS for molar mass analysis of polymers, especially polysaccharide derivatives. The methodology has been successfully applied to different industrially important derivatives of starch and cellulose. Among the results the separation enabled the detection of ultra-high molar mass components in cellulose derivatives and facilitated further investigations on its chemical structure. The investigations include discussions on suitable experimental conditions, such as polymer concentration, flow rate and choice of programmed field function, for the separation of polysaccharide derivatives with FFF. The MALS technique, especially the extrapolation procedure involved, was investigated with respect to the accuracy of the determined molar masses for very large polymers.
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