Atomistic Investigation of Poly(3-hexylthiophene) Adhesion on Nanostructured Titania

We studied the adhesion of poly(3-hexylthiophene) on a nanostructured
titanic surface in vacuo by means of model potential molecular dynamics.
We generated large-scale atomistic models of nanostructured titania
surfaces {[}consisting of spherical nanocaps on top of a (110) rutile
surface] and we studied the adhesion of an oligothiophene as a function
of local curvature and roughness. In the limit of a perfect planar
Surface, the maximum adhesion energy is calculated to be as large as 0.6
eV/monomer, and it corresponds to the oligothiophene oriented along the
{[}(1) over bar 10] direction of the surface. Deformations of the
polymer are observed due to incommensurability between the titanic and
the polymer lattice parameters. When the surface is nanostructured,
adhesion of the polymer is affected by the local morphology and it
nonmonotonic dependence on the surface curvature is observed. The
atomistic results are explained by a simple continuum model that
includes the strain energy of the polymer and its electrostatic
interaction with the local surface charge.