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Atomistic investigation of the poly(3-hexylthiophene) adhesion on nanostructured titania

We study the adhesion of poly(3-hexylthiophene) on nanostructured titania surface in vacuo by means of model potential molecular dynamics. We generate large scale atomistic models of nanostructured titania surfaces (consisting of spherical nanocaps on top of a (110) rutile surface) and we study the adhesion of an oligothiophene as a function of their 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 per monomer, and it corresponds to the oligothiophene oriented along the [$\bar{1}10$] direction of the surface. Deformations of the polymer are observed due the incommensurability between the titania and the polymer lattice parameters. When the surface is nanostructured, the adhesion of the polymer is affected by the local morphology and a nonmonotonic dependence on the surface curvature is observed. The atomistic results are explained by a simple um model that includes the strain energy of the polymer and its electrostatic interaction with the local surface charge.