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Updated: May 29, 2026

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Molecular weight effect on the formation of β phase poly(9,9'-dioctylfluorene) in dilute solutions
Craig W Cone1, Ryan R Cheng, Dmitrii E Makarov
1Department of Biochemistry and Chemistry, University of Texas at Austin, Austin, Texas 78712, United States.
Abstract:
The effect of molecular weight on the formation of β phase poly(9,9'-dioctylfluorene) (PF8) was studied in dilute solutions. Temperature-dependent fluorescence experiments of unique synthetic batches as well as size-excluded single batches of polyflourene were studied. Each batch had unique molecular weight, tetrahedral defect concentration, and polydispersity index (PDI). Polyflourene was found to exhibit a temperature-dependent transition between two phases with distinct electronic transition signatures: the α (primary) phase and the β (secondary) phase. In dilute solutions, the temperature at which the polymer exhibited a conversion between these phases showed a clear dependence on molecular weight. We model this transition temperature for β phase formation using the mean field theory for the coil-globule transition developed by Isaac Sanchez. Results show that temperature affects the average end-to-end distance corresponding to increases in secondary electronic absorption and that the dependence on temperature related to the coil-globule transition.
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