Accurate molecular weight distribution of polymers using thermal field‐flow fractionation with deconvolution to remove system dispersion

摘要

AbstractThermal field‐flow fractionation (ThFFF) is an elution process that separates polymeric materials by molecular weight. Elution profiles thus provide approximations to the molecular weight distributions of polymers. The accuracy of such approximate distributions is expected to be improved by accounting for the effect on the elution profile of band‐broadening processes in the FFF system. Fortunately this intrinsic band broadening, referred to as system dispersion, is theoretically well‐defined in ThFFF. In this article we present an algorithm that corrects ThFFF elution profiles by removing system dispersion. The program is applied to ThFFF fractograms of standard polymers having both narrow and broad molecular weight distributions. The increased accuracy obtained by accounting for system dispersion is demonstrated. For the narrow standard, deconvolution shows that the polydispersity (weight/number‐average mol. wt.) is only 1.004. For the broad standard, NBS 706, the molecular weight distribution and parameters obtained agree well with previously published results. Application to a simulated fractogram resulting from mixing five narrow standards helps define the conditions under which accurate molecular weight information can be re