Structural and morphological control of poly(3-alkyl thiophenes) (P3ATs), and in particular the well-studied poly(3-hexyl thiophene) (P3HT), is needed to increase their favorable electronic properties. P3ATs tend to be soluble in common solvents, but many aspects of their crystallization are not well understood. Semicrystalline regioregular P3ATs order in three dimensions with conformational ordering along the backbone, p-p stacking of flat polymer chains, and lamellar stacking between chains. The exact dimensions of the crystal packing can change based on a number of variables, including molecular weight or crystallization temperature. Because of this variability, a precise evaluation of the enthalpy of fusion of an ideal crystal (?H0u)for the well-studied P3HT is still debated in the literature. Using values of densities measured by pycnometery and heat of melting by differential scanning calorimetry, a value for (?H0u) is extrapolated from P3HT crystallized at different temperatures and times. The density of the amorphous portion of the semi-crystalline regio-regular P3HT is also determined from this analysis. 

Density and enthalpy of poly(3-hexylthiophene) crystallization

245th National Meeting (2013)

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