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Line-Shape Analysis of Poly(3-dodecylthiophene): A Study of Layer Disorder Through the Liquid Crystalline Polymer Transition

Published

Author(s)

T J. Prosa, J Moulton, A Heeger, M J. Winokur

Abstract

The nature of the structural ordering within semi-crystalline poly(3-dodecylthiophene) films has been analyzed using a Warren-Averbach line-shape analysis which includes up to five orders of the (h00) lattice reflections. This analysis yields a semi-quantitative measure of the volume averaged crystallize sizes, the lattice parameter variations, and the disorder fluctuations. The progressions of these quantities has been followed through a liquid crystal polymer (LCP) phase transition which occurs in the vicinity of 60 degrees}C. The pronounced peak width narrowing the low order(h00) reflections observed on heating is found to be essentially uncorrelated with the theorized annealing induced increases in average crystallite size. The major contribution to the observed peak profile narrowing arises from systematic variations in the microscopic heterogenities and fluctuations. Moreover, we observe an anomalously large increase in the high order (h00)(h=3,4 and 5) peak widths at temperatures spanning that of the thermotropic LCP transition. This effect is to be strongly correlated with a maximum in the disorder fluctuations and this relationship suggests an underlying mechanism for the nature of the LCP transition.
Citation
Macromolecules

Keywords

crystal size, disorder, liquid crystal, peak broadening, phase transition, polymers, Warren-Averbach, x-ray diffraction

Citation

Prosa, T. , Moulton, J. , Heeger, A. and Winokur, M. (2008), Line-Shape Analysis of Poly(3-dodecylthiophene): A Study of Layer Disorder Through the Liquid Crystalline Polymer Transition, Macromolecules (Accessed April 12, 2024)
Created October 16, 2008