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Estimation of width of narrow molecular-weight distributions by size-exclusion chromatography with concentration and
M Netopilík1, S Podzimek, P Kratochvíl
1Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague. netopil@imc.cas.cz
Abstract:
A new method for the estimation of the weight-to-number-average molecular-weight ratio, Mw/Mn of polymers with a narrow molecular-weight distribution, approximated by log-normal distribution, is proposed using size-exclusion chromatography (SEC) with concentration and light-scattering detectors. From experimental data, the Mw/Mn ratios are calculated by two procedures: one using the concentration and light-scattering elution curve for the polymer measured, and the other based on the concentration elution curve and calibration line for a wide range of molecular masses. An iteration method has been developed making the two Mw/Mn ratios converge. The method was applied to a series of narrow molecular-weight distribution polystyrene standards.