Entropic effects in carbon nanotubes-templated crystallization of Poly(3-alkyl thiophenes, P3HT, P3OT)

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32 Scopus citations

Abstract

A significant increase in polymer crystallinity is reported in composites of carbon-nanotubes (CNT) and Poly(3-octylthiophene-2,5-diyl), P3HT and Poly(3-octylthiophene-2,5-diyl), P3OT; Differential scanning calorimetry (DSC) reveal an increase from about 40% crystallinity of the native P3HT to ∼62% in composites containing 25 wt% MWNT. A similar behavior is observed in P3OT with ∼68% crystallinity, a double crystallization peak and higher melting temperature than the native polymers. The effect is unique to CNT and is not induced by fullerenes or graphene layers. High-resolution transmission electron microscopy, (HRTEM) of CNT-polymer dispersions reveal chains stacked upon the CNT in an elongated, stretched conformation. Following a detailed molecular study by Bernardi et al. and the HRTEM observations the DSC results are attributed to a CNT-mediated entropic effect: due to their intrinsic, 1D cylindrical shape the CNT impose an increased conjugation length on chains adsorbed and stacked upon dispersed CNT. Crystallization thus commences from a heterogeneous mixture of native chains and chains with a longer persistence length (higher effective rigidity) and consequentially a lower effective height of the entropic barrier for crystallization. The findings offer a new insight into the origins of CNT-induced polymer nucleation.

Original languageEnglish
Pages (from-to)6399-6405
Number of pages7
JournalPolymer
Volume54
Issue number23
DOIs
StatePublished - 1 Nov 2013
Externally publishedYes

Keywords

  • Carbon nanotubes
  • Entropic nucleation
  • Polymer crystallization

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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