Real-time observation of conformational switching in single conjugated polymer chains
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Conjugated polymers (CPs) are an important class of organic semiconductors that combine novel optoelectronic properties with simple processing from organic solvents. It is important to study CP conformation in solution to understand the physics of these materials and because it affects the properties of solution-processed films. Single-molecule techniques are unique in their ability to extract information on a chain-to-chain basis; however, in the context of CPs, technical challenges have limited their general application to host matrices or semiliquid environments that constrain the conformational dynamics of the polymer. We introduce a conceptually different methodology that enables measurements in organic solvents using the single-end anchoring of polymer chains to avoid diffusion while preserving polymer flexibility. We explore the effect of organic solvents and show that, in addition to chain-to-chain conformational heterogeneity, collapsed and extended polymer segments can coexist within the same chain. The technique enables real-time solvent-exchange measurements, which show that anchored CP chains respond to sudden changes in solvent conditions on a subsecond time scale. Our results give an unprecedented glimpse into the mechanism of solvent-induced reorganization of CPs and can be expected to lead to a new range of techniques to investigate and conformationally manipulate CPs.
Tenopala Carmona , F , Fronk , S , Bazan , G C , Samuel , I D W & Penedo-Esteiro , J C 2018 , ' Real-time observation of conformational switching in single conjugated polymer chains ' Science Advances , vol 4 , no. 2 , eaao5786 . DOI: 10.1126/sciadv.aao5786
Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY).
This work was supported by the Engineering and Physical Sciences Research Council UK (EPSRC) (project EP/N009886/1). F.T.-C. thanks EPSRC (Grant EP/L015110/1). S.F. acknowledges support from the National Science Foundation (Grant DMR 1411240). I.D.W.S. acknowledges support from a Royal Society Wolfson research merit award.
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