Gel permeation chromatography (GPC) is at the center of the characterization of polymers. This characterization method is performed across the duration of the material’s lifecycle. This process follows the material after the first polymerization, before and after it is purified, after post-polymerization modification, in the final product, and after degradation, failure, and/or aging.
The main aim of using GPC to analyze polymers is to characterize their molar mass distributions and molecular weights. Identifying the molecular weight is driven by a number of motivations, such as estimating how the properties of a product will be impacted and understanding the effectiveness of a reaction.
Along with molecular weight, researchers aim to understand changes in the sample’s structure, compositional changes, solution viscosity, branching, and size. The OMNISEC multi-detection GPC system delivers this data with the highest degree of sensitivity.
A fusion of light scattering, refractive index, viscometer, and UV/vis spectrometer detectors are used in the OMNISEC to deliver a more thorough characterization compared to the relative molecular weight results achieved when using RI detection alone.
Polysiloxanes are a complex material to investigate using GPC, because when the most widespread polysiloxane, polydimethylsiloxane (PDMS), is analyzed in the regular organic solvent for GPC, THF, the RI peaks are very small and are not found in the light scattering detectors.
The PDMS signals in both of these detectors are significant when analyzed in toluene. This is caused by the material’s refractive index increment (dn/dc) (please read this article for additional information on the dn/dc value).
Polysiloxanes are commonly employed in a variety of applications because they are hydrophobic, show high chemical stability, are unreactive, have strong electrical insulation, and can be used to produce various types of material, for example adhesives, foams, gels, lubricants, and elastomers. The chemical functionality integrated into a polysiloxane can be selected to impart particular properties to the polysiloxane.
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This information has been sourced, reviewed and adapted from materials provided by Malvern Panalytical.
For more information on this source, please visit Malvern Panalytical.