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Solvatochromism and conformational changes in fully dissolved poly(3-alkylthiophene)s
Gregory M Newbloom1, Stephanie M Hoffmann, Aaron F West
1Department of Chemical Engineering, University of Washington , Box 351750, Seattle, Washington 98195-1750, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|December 9, 2014
Summary
Changes in polymer optical properties are not solely due to chain conformation. Specific polymer-solvent interactions, not generalized theories, influence poly(3-alkylthiophene)s (P3ATs) behavior in solution.
Area of Science:
- Polymer Science
- Spectroscopy
- Computational Chemistry
Background:
- Absorption spectroscopy probes polymer optical properties, often linked to chain conformation and conjugation length.
- Peak position shifts in optical spectra are frequently attributed to changes in polymer chain stiffness.
Purpose of the Study:
- Investigate the relationship between poly(3-alkylthiophene)s (P3ATs) conformation and optical properties.
- Clarify the influence of solvent environments on polymer behavior and spectral characteristics.
Main Methods:
- Utilized ultraviolet-visible (UV-vis) spectroscopy, small-angle neutron scattering (SANS), and all-atom molecular dynamics (AA-MD) simulations.
- Analyzed variations in radius of gyration and Kuhn length with alkyl chain length and solvent.
Main Results:
- SANS revealed conformational changes in P3ATs influenced by alkyl chain length and solvent.
- Dissolved P3HT chains exhibited increased rigidity in solvents promoting self-assembly.
- Observed optical property shifts in P3ATs did not correlate with conformational changes or generalized solvent-solute interactions.
Conclusions:
- Generalized solvatochromic theory inadequately explains observed optical property changes.
- AA-MD simulations offer insights into specific polymer-solvent interactions.
- Further research is needed to understand the precise role of solvent molecules in local polymer conformation and optical properties.
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