The phase behavior of many conjugated polymers is rich but not yet fully explored. Stiff chain conformations and planar ring-like structures can promote both crystalline and liquid crystalline phases. Recent computational efforts that rely on atomistic and field-theory simulations have identified the nematic coupling parameter for polymers such as poly(3-hexylethiophene-2,5-diyl) (P3HT) and as a consequence the isotropic-to-nematic transition temperature. Herein, model predictions are combined with experimentally determined values of the equilibrium melting temperature as a function of chain length to provides the complete phase behavior for P3HT. Additionally, since a full description of the phase behavior requires proper accounting for the regioregularity of the chain, we derive a thermodynamic relationship to predict this behavior as a function of both chain length and regioregularity and discuss its impact on the expected phase diagram.
and Gomez, E.
Phase Behavior of Poly(3-hexylthiophene-2,5-diyl), Journal of Polymer Science Part B-Polymer Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=919411
(Accessed June 9, 2023)