Composition and molecular weight analysis of styrene-acrylic copolymers using thermal field-flow fractionation

J. Ray Runyon, S. Kim Ratanathanawongs Williams

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

Thermal field-flow fractionation coupled with online multiangle light scattering, differential refractive index and quasielastic light scattering (ThFFF-MALS/dRI/QELS) was used to simultaneously determine the molecular weight (MW) and composition of polystyrene-poly(n-butyl acrylate) (PS-PBA) and polystyrene-poly(methyl acrylate) (PS-PMA) copolymers. The online measurement of the normal diffusion coefficient (D) by QELS allowed calculation of the copolymer thermal diffusion coefficient (DT) of sample components as they eluted from the ThFFF channel. DT was found to be independent of MW for copolymers with similar compositions and dependent on composition for copolymers with similar MW in a non-selective solvent. By using a solvent that is non-selective to both blocks of the copolymer, it was possible to establish a universal calibration plot of DT versus mole fraction of one of the monomer chemistries comprising the copolymer. PS-PBA and PS-PMA linear diblock polymers were determined to vary in composition from 100/0 to 20/80wt% PS/acrylate and ranged in MWs between 30 and 360kDa. The analysis of a PS-PBA miktoarm star copolymer revealed a polydisperse material with a weight percent PBA of 50-75% and MW ranging from 100 to 900kDa. The presented ThFFF-MALS/dRI/QELS method allowed rapid characterization of polymers with MW and chemical distributions in a single analysis.

Original languageEnglish (US)
Pages (from-to)6774-6779
Number of pages6
JournalJournal of Chromatography A
Volume1218
Issue number38
DOIs
StatePublished - Sep 23 2011
Externally publishedYes

Keywords

  • Composition
  • Copolymer
  • Light scattering
  • Polyacrylate
  • Thermal diffusion
  • Thermal field-flow fractionation

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

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