Thermal and structural characteristics of oligo(3-hexylthiophene)s (3HT)n, n = 4-36

Felix Peter Vinzenz Koch, Martin Heeney, Paul Smith

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104 Scopus citations


This study is concerned with the thermal and structural characteristics of a series of precisely defined, monodisperse, regioregular oligo(3- hexylthiophene)s (3HT)n of n = 4-36. We find that these model compounds can feature two distinctly different solid-state structures, i.e., the more classical polymorph Form I in which the hexyl side-chains are not interdigitated and Form II in which they are. The thermodynamic equilibrium melting temperatures of these phases differ as much as ∼180 C, with 116 C for Form II and 298 C for Form I. Furthermore, polymorph II featured an enthalpy of melting of ∼3 times that of Form I and a rate of crystallization that is ∼1 order of magnitude lower than that of Form I. A crossover of the thermodynamically preferred Form II into the kinetically favored Form I is observed at a number of repeat units of 12. In the regime 10 ≤ n ≤ 21 the oligo(3-hexylthiophene)s could readily be reversibly converted from one polymorph to another by appropriate processing treatments. The relevance of these findings for the polymeric form (P3HT) is discussed. © 2013 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)13699-13709
Number of pages11
JournalJournal of the American Chemical Society
Issue number37
StatePublished - Sep 18 2013
Externally publishedYes

Bibliographical note

Generated from Scopus record by KAUST IRTS on 2023-02-14

ASJC Scopus subject areas

  • Biochemistry
  • Colloid and Surface Chemistry
  • Chemistry(all)
  • Catalysis


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