title: Fractionation of Poly(butyl methacrylate) by Molecular Topology Using Multidetector Thermal Field-Flow Fractionation.
abstract: Thermal field-flow fractionation (ThFFF) is an interesting alternative to column-based fractionation being able to address different molecular parameters including size and composition. Until today it has not been shown to be able to fractionate polymers of similar molar masses and chemical compositions by molecular topology. The present study demonstrates that poly(butyl methacrylates) with identical molar masses can be fractionated by ThFFF according to the topology of the butyl group. The influence of the solvent polarity on the thermal diffusion behavior of these polymers is presented and it is shown to have a significant influence on the fractionation of poly(n-butyl methacrylate) and poly(t-butyl methacrylate). Fractionation improves with increasing solvent polarity and solvent polarity may have a greater influence on fractionation than solvent viscosity. It is found that the thermal diffusion coefficient, D(T), as well as the hydrodynamic diameter, D(h), exhibit increasing trends with increasing solvent polarity. The solvent quality has a significant influence on the fractionation. It is found that cyclohexane, being a theta solvent for poly(t-butyl methacrylate) but not for poly(n-butyl methacrylate), significantly improves the fractionation of the samples by decreasing the diffusion rate of the former but not the latter.
authors.affiliation: Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, 7602, Matieland, South Africa.
authors.forename: Guilaume
authors.initials: G
authors.lastname: Greyling
authors.affiliation: Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, 7602, Matieland, South Africa.
authors.forename: Harald
authors.initials: H
authors.lastname: Pasch
mesh_terms: D008689:Methacrylates / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D008689:Methacrylates; C116863:poly(butyl methacrylate)
keywords: poly(n-butyl methacrylate); poly(t-butyl methacrylate); solvent polarity; thermal diffusion; thermal field-flow fractionation