COSMO-RS and solvatochromic parameters to investigate the correlation between P3HT assembly and the nucleophilicity of solvents

• COSMO-RS σ-profiles are computed for 48 solvent mixtures.
• P3HT assembly is examined using solvatochromic parameters and COSMO-RS.
• Solvent nucleophilicity is critical to the structural order of P3HT aggregates.

The use of specific binary solvent mixtures to drive the self-assembly of semiconducting polymers, such as poly(3-hexylthiophene) (P3HT), as a route to well-organized films and optoelectronic composites has garnered a lot of interest. To date, the dominant intermolecular forces in these mixtures have only been partially scrutinized. The σ-profiles obtained from the Conductor-like Screening Model for Real Solvents (COSMO-RS) calculations are used to assess the lipophilic, electrophilic, and nucleophilic characteristics of 48 binary solvent mixtures. Correlations between these characteristics and experimentally measured Kamlet–Taft (α, β, π  *) and ETN solvatochromic parameters are examined to assess the nature of the solvent-polymer interactions directing the assembly of P3HT into macromolecular architectures. The experimental and computed σ-profiles results are in good agreement and indicate that while the polarity of the solvent impacts the general solubility behavior of P3HT, the nucleophilicity of the solvent mixture is a key factor in dictating the structural order of P3HT aggregates.

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