The Effect of Glycol Side Chains on the Assembly and Microstructure of Conjugated Polymers

Stefania Moro, Nicholas Siemons, Oscar Drury, Daniel A. Warr, Thomas A. Moriarty, Luís M.A. Perdigão, Drew Pearce, Maximilian Moser, Rawad K. Hallani, Joseph Parker, Iain McCulloch, Jarvist M. Frost, Jenny Nelson, Giovanni Costantini

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Conjugated polymers with glycol-based chains, are emerging as a material class with promising applications as organic mixed ionic-electronic conductors, particularly in bioelectronics and thermoelectrics. However, little is still known about their microstructure and the role of the side chains in determining intermolecular interactions and polymer packing. Here, we use the combination of electrospray deposition and scanning tunneling microscopy to determine the microstructure of prototypical glycolated conjugated polymers (pgBTTT and p(g2T-TT)) with submonomer resolution. Molecular dynamics simulations of the same surface-Adsorbed polymers exhibit an excellent agreement with the experimental images, allowing us to extend the characterization of the polymers to the atomic scale. Our results prove that, similarly to their alkylated counterparts, glycolated polymers assemble through interdigitation of their side chains, although significant differences are found in their conformation and interaction patterns. A model is proposed that identifies the driving force for the polymer assembly in the tendency of the side chains to adopt the conformation of their free analogues, i.e., polyethylene and polyethylene glycol, for alkyl or ethylene glycol side chains, respectively. For both classes of polymers, it is also demonstrated that the backbone conformation is determined to a higher degree by the interaction between the side chains rather than by the backbone torsional potential energy. The generalization of these findings from two-dimensional (2D) monolayers to three-dimensional thin films is discussed, together with the opportunity to use this type of 2D study to gain so far inaccessible, subnm-scale information on the microstructure of conjugated polymers.

Original languageEnglish (US)
Pages (from-to)21303-21314
Number of pages12
JournalACS Nano
Volume16
Issue number12
DOIs
StatePublished - Dec 27 2022
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy

Keywords

  • conjugated polymers
  • glycolated side chains
  • microstructure
  • molecular dynamics
  • scanning tunneling microscopy

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