Selective synthesis of poly(p-oxybenzoyl) by fractional polycondensation: Enhancement of selectivity by shearing

Toshimitsu Ichimori, Shinichi Yamazaki, Kunio Kimura

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Abstract

The influence of shear flow, especially the timing for the application of shearing, was examined to enhance the selectivity for the preparation of poly(p-oxybenzoyl) (Pp-OB) by using hydrodynamically induced phase separation during polymerization of 4-(4-acetoxybenzoyloxy)benzoic acid (p-ABAD) and m-acetoxybenzoic acid (m-ABA). The polymers containing few m-oxybenzoyl (m-OB) moieties were obtained as precipitates even at high content of m-OB moiety in feed (πf) under shear flow. The content of m-OB moiety in the precipitates (πp) prepared under shearing throughout the polymerization at the shear rate (γ) of 489 s-1 was 6.3 mol % even at πf of 60 mol %. Especially, the Pp-OB was obtained as the precipitates at πf of less than 50 mol %. The timing of the application of the shearing influenced the selectivity significantly, and the shearing just after the precipitation of the oligomers started was quite efficient to enhance the selectivity more. The πp of the precipitates prepared with shearing at γ of 489 s-1 just after the precipitation was only 3.9 mol % even at πf of 60 mol %. The shear flow reduced the difference in the reactivity between p-ABAD and m-ABA, resulting in the decrease in the selectivity with regard to the formation of p-oxybenzoyl homo-oligomer. However, the shear flow enhanced the difference in the miscibility between homo-oligomers and co-oligomers. This change in the miscibility by shear flow brought about the more rapid precipitation of homo-oligomers, leading to the enhancement of the selectivity.

Original languageEnglish
Pages (from-to)4613-4617
Number of pages5
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume49
Issue number21
DOIs
Publication statusPublished - Nov 1 2011

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Keywords

  • crystallization
  • polycondensation
  • polyesters
  • selective synthesis
  • shear

ASJC Scopus subject areas

  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry

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