Synthesis and characterization of hyperbranched aromatic poly(ether imide)s with varying degrees of branching

D. Scott Thompson, Larry J. Markoski, Jeffrey S. Moore, Ibrahim Sendijarevic, Anand Lee, Anthony J. McHugh

Research output: Contribution to journalArticle

Abstract

A series of high molecular weight hyperbranched poly(ether imide)s (HBPEI), derived from the AB2 monomer N-[3,5-di(tert-butyldimethylsilyloxy)phenyl]-4-fluorophthalimide (1), were synthesized in a single-step process involving a rapid fluoride-catalyzed arylation reaction. NMR analysis of the degree of branching shows that changes in the polymerization reaction time, from 2.5 to 20.0 min, result in hyperbranched polymers with degrees of branching ranging from 66% to 42%, respectively. Reactions of selected model compounds show that changes in the degree of branching are a result of molecular rearrangements occurring via a transetherification mechanism. Such rearrangements lead to an increase in Mw while Mn remains relatively constant. Correlations between rheological data and the degree of branching of the hyperbranched poly(ether imide)s were observed. For solutions of the hyperbranched poly(ether imide)s, rheological measurements showed that shear thinning and normal stress effects increased as the degree of branching decreased and that birefringence as a function of shear rate increased with decreasing degree of branching. While strong correlations between the degree of branching and rheological properties exist, light scattering GPC measurements show that Mw increases significantly with reaction time. This variation in Mw suggests that the differences in rheological properties may be largely due to changes in molecular weight and makes it difficult to determine the role that changes in the degree of branching, which are manifested in altered molecular architecture, have on macroscopic physical properties.

Original languageEnglish (US)
Pages (from-to)6412-6415
Number of pages4
JournalMacromolecules
Volume33
Issue number17
DOIs
StatePublished - Aug 22 2000

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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