Entanglements in P3HT and their influence on thin-film mechanical properties: Insights from molecular dynamics simulations

Naga Rajesh Tummala, Chad Risko, Christopher Bruner, Reinhold H. Dauskardt, Jean-Luc Bredas

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

Due to their inherent mechanical flexibility and stretchability, organic-based electronic devices have garnered a great deal of academic and industrial interest. Here, molecular-dynamics simulations are used to examine the molecular-scale details that govern the relationships among molecular weight, chain entanglement, persistence length, and the elastic characteristics of the widely studied π-conjugated polymer poly-(3-hexyl thiophene), P3HT. Oligomers containing at least 50 monomer units are required in the simulations to observe elastic behavior in P3HT, while much longer chains are required to ensure description of appropriate levels of entanglement: only when the molecular weight is greater than 50 kDa, that is, oligomers with approximately 400 monomer units, is truly entangled behavior observed. Interestingly, results from primitive path analysis of amorphous P3HT matches well with the observed onsets of inter-chain excitonic coherence with increased molecular weight. The simulations also indicate that the P3HT modulus saturates at 1.6 GPa for chain lengths of 50–100 monomers, a result that compares well with experimental results. This work highlights the care that needs to be taken to accurately model P3HT morphologies in relation to experimental measurements. © 2015 The Authors. Journal of Polymer Science Part B: Polymer Physics Published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015
Original languageEnglish (US)
Pages (from-to)934-942
Number of pages9
JournalJournal of Polymer Science Part B: Polymer Physics
Volume53
Issue number13
DOIs
StatePublished - Apr 8 2015

ASJC Scopus subject areas

  • Materials Chemistry
  • Polymers and Plastics
  • Physical and Theoretical Chemistry
  • Condensed Matter Physics

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