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Keywords:

  • conducting polymers;
  • fractionation of polymers;
  • high performance liquid chromatography (HPLC);
  • molecular weight distribution/molar mass distribution;
  • seperation of polymers

Abstract

In this article, we have investigated a temperature-rise fractionation procedure for poly(3-hexyl thophene) (P3HT) and poly(3-octyl thophene) (P3OT) that provides well-defined molecular weight (MW) fractions with improved molecular weight distributions (MWD) when compared with Soxhlet extraction. This process involves dispersing the material over C18-boned silica stationary phase in a jacketed column and using incremental rises in column temperature (Tcol) to gradually improve solvent quality and selectively dissolve higher molecular weight samples with a narrow polydispersity (PDI). Fractionation of P3HT with ΔTcol = 5 °C in methylene chloride (MC) yielded 7 fractions ranging from Mp of 20 to 53 kg/mol with an average PDI of 1.80 compared with a mother sample of 3.10. Predominant recovery of P3HT was acquired for fractions with Tcol > 20 °C (30 wt %). Subsequent separation of P3OT in methylene chloride, with a reduced ΔTcol of 3 °C per fraction, due to increased solubility from the longer alkyl chain, generated 8 fractions with a weight range of Mn = 22 to 57 kg/mol with an mean PDI of 1.23 with the mother sample having PDI = 2.34, demonstrating the tunability of this method. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2547–2555, 2009