Solution-crystallization and related phenomena in 9,9-dialkyl-fluorene polymers. II. Influence of side-chain structure

Aleksandr Perevedentsev, Paul N. Stavrinou, Paul Smith, Donal D.C. Bradley

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16 Scopus citations

Abstract

Solution-crystallization is studied for two polyfluorene polymers possessing different side-chain structures. Thermal analysis and temperature-dependent optical spectroscopy are used to clarify the nature of the crystallization process, while X-ray diffraction and scanning electron microscopy reveal important differences in the resulting microstructures. It is shown that the planar-zigzag chain conformation termed the β-phase, which is observed for certain linear-side-chain polyfluorenes, is necessary for the formation of so-called polymer-solvent compounds for these polymers. Introduction of alternating fluorene repeat units with branched side-chains prevents formation of the β-phase conformation and results in non-solvated, i.e. melt-crystallization-type, polymer crystals. Unlike non-solvated polymer crystals, for which the chain conformation is stabilized by its incorporation into a crystalline lattice, the β-phase conformation is stabilized by complexation with solvent molecules and, therefore, its formation does not require specific inter-chain interactions. The presented results clarify the fundamental differences between the β-phase and other conformational/crystalline forms of polyfluorenes.
Original languageEnglish (US)
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume53
Issue number21
DOIs
StatePublished - Nov 1 2015
Externally publishedYes

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