433374 Solvatochromism and Conformational Changes in Fully Dissolved Poly(3-alkylthiophene)s

Wednesday, November 11, 2015: 2:15 PM
251B (Salt Palace Convention Center)
Gregory Newbloom1, Stephanie Hoffmann1, Aaron West1, Melissa Gile1, Prakash Sista2, Hoi-Ki Cheung2, Christine Luscombe2, Jim Pfaendtner1 and Lilo Pozzo3, (1)Chemical Engineering, University of Washington, Seattle, WA, (2)Material Science & Engineering, University of Washington, Seattle, WA, (3)Chemical Engineering, University of Washington, Seattle

Absorption spectroscopy is commonly utilized to probe optical properties that can be related, among other things, to the conformation of single, isolated conjugated polymer chains in solution. It is frequently suggested that changes in peak positions of optical spectra result from variations in the stiffness of polymer chains in solution because this modifies the conjugation length. In this talk, we utilize ultraviolet-visible (UV-vis) spectroscopy, small angle neutron scattering (SANS) and all atom molecular dynamic (AA-MD) simulations to closely probe the relationship between the conformation of single-chains of poly(3-alkylthiophene)s (P3ATs) and their optical properties. SANS results show variations in the radius of gyration and Kuhn length as a function of alkyl chain length, and structure, as well as the solvent environment. Furthermore, both SANS and MD simulations show that dissolved P3HT chains are more rigid in solvents where self-assembly and crystallization are possible. Shifts in P3AT optical properties were also observed for different solvent environments. However, these changes were not correlated to the changes in polymer conformation. Furthermore, changes in optical properties could not be perfectly described by generalized solvent-solute interactions. AA-MD simulations provide new insights into specific polymer-solvent interactions not accounted for in generalized solvatochromic theory. This work highlights the need for experiments and molecular simulations that further inform the specific role of solvent molecules on local polymer conformation and on optical properties.

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See more of this Session: Conjugated Polymers
See more of this Group/Topical: Materials Engineering and Sciences Division