Building organosilica hybrid nanohemispheres via thiol-ene click reaction on alumina thin films deposited by atomic layer deposition (ALD).

The present work shows a surface-induced preparation of sub-100 nm organosilica nanohemispheres on atomic layer deposited (ALD) AlO thin films, which was achieved by cooperative condensation/hydrolysis and thiol-ene click chemical reactions. The two-step synthetic approach consists of an initial silanization of the AlO film with vinyltrimethoxysilane (VTMS), followed by a photo-promoted growth of surface-bound nanoparticles in the presence of (3-mercaptopropyl)trimethoxysilane (MPTMS). Characterization by means of FE-SEM, XPS and EDS points towards the growth of the nanohemispherical structures being governed by an initial nucleation of thiolated organosilica seeds in solution as a result of self-condensation of MPTMS and oxidation of thiols to disulfides. Once bound to the vinyl terminated AlOvia photo-assisted thiol-ene coupling, these seeds promote area-selective growth of the nanoparticles through binding of further MPTMS from the solution. After an additional ALD deposition of ZnO, the resulting thin hybrid film exhibits enhanced hydrophobicity when compared to ZnO films deposited directly on AlO under the same processing conditions.