Polymer brushes grafted from nanostructured zinc oxide layers – Spatially controlled decoration of nanorods

Abstract

Poly(N-isopropylacrylamide) (PNIPAM) brushes were grafted from ZnO nanostructured layers with nanorod and hexagonal grains morphologies via Atom Transfer Radical Polymerization in various methanol/water mixtures. The brushes’ growth was followed using Quartz Crystal Microbalance and the obtained hybrid systems were characterized microscopically and using XPS profiling. The studied nanostructured ZnO has high potential for e.g., photovoltaic, sensor applications that may be enhanced in nanocomposites with spatial and compositional control on the organic/inorganic interface. Such systems were realized by grafting polymer brushes from both the convex tops of nanorods and concave areas between them. It was revealed that the growth of PNIPAM brushes on such nanostructured substrates may be controlled by varying the solvent composition. The polymerization performed at higher methanol content (xMe ≈ 0.31) led to decoration of the nanorods only with thin polymer layers around them while for the lower content the polymerization proceeded much faster leading to formation of the thick coating covering their tops. Importantly, such a layer did not block the brushes growth in the confined intercolumnar space. Thus, fine tuning of the solvent mixture should lead to desired relations between the mass/thickness of polymer brushes grafted from convex and concave areas that are crucial for applications of such nanocomposites.