Confinement of Semiconductor ZnO Nanoparticles in Block Copolymer Nanostructure

The morphology and the electrical properties of hybrid nanocomposites characterized by the dispersion of ZnO nanoparticles (NPs), a n-type semiconductor, within an organic nanostructured matrix of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) block copolymer are presented. A selective inclusion of NPs only into the lamellar PS nanodomains of the block copolymer matrix has been achieved by synthetizing ZnO NPs coated with n-hexadecylamine (HDA) and tert-butylphosphonic acid (TBPA) molecules and subsequent thermal annealing of the nanocomposites ZnO NPs/PS-b-PMMA. Thermal treatments have allowed obtaining in one step the vertical orientation of the lamellar BCP nanodomains and the migration of the NPs to the PS domains, resulting in the formation of nanocomposites characterized by a precise control of the position of n-semiconductor ZnO NPs. Current-voltage measurements on the nanocomposites have indicated the presence of continuous path of charge carriers in the BCP films when the ZnO NPs content is above a threshold concentration. The experimental results have allowed the setup and validation of a theoretical protocol to study heterogeneous interfaces. In particular, the interaction of ZnO most stable nonpolar surface with prototypical capping agents has been analyzed by using density functional theory (DFT) calculations.