|J.Ciric at rug.nl|
Improved characterization techniques for branched polymers
One of the most fascinating parts of polymer science is to understand the relationship between molecular architecture and the physical properties of polymers; to quantify the effects and even to go further and be able to predict how the molecular structure could be altered to modify physical properties.
Variables such as molecular weight, polydispersity and the presence and degree of branching in polymers have huge implications not only for the final solid state properties of a product but also for properties in the melt.
Branched polymers are of a great scientific and practical interest. For example, short-chain and long-chain branching have been extensively used to modify properties such as crystallinity and viscosity.
Good non-destructive characterization techniques for branched polymers are rare. Size-Exclusion-Chromatography; Flow-Field-Flow-Fractionation with Multi Angle Light Scattering detection (SEC-FlFFF-MALS) might result in the establishment of improved characterization protocols for branched polysaccharides and also other branched polymers. In this study, we will synthesize well-defined linear and branched polysaccharides such as amylose and (hyper)branched amylose (HBA) by combined use of enzymes from the transferase family for characterization with SEC-FlFFF-MALS.
Phosphorylase is used to catalyze the polymerization of glucose-1-phosphate in order to obtain linear polysaccharide chains with α-(1→4) glycosidic linkages.
With the addition of glycogen branching enzyme α-(1→4) linked oligosaccharides are transferred from the non-reducing end to α-(1→6) position, resulting in a (hyper)branched structure.
The molecular weight of synthesized polymers is calculated from quantitative spectroscopic determination of the released inorganic phosphate. Degree of branching of HBA is determined by 1H-NMR and polydispersity of the branches is analyzed with MALDI-ToF experiments.
UV spectroscopy, 1H-NMR and MALDI-ToF give enough information for the previously mentioned development of improved characterization protocols.
Since SEC is widely used for molar mass distribution analysis of amylose and debranched amylopectin and FlFFF-MALS as a versatile technique to obtain detailed information on the branching features of amylopectin, we think that the characterization via this combination of techniques could open up complete new insight into the characterization of branched polymers.
|Laatst gewijzigd:||01 juli 2015 10:53|