The distribution of hydrophobized inorganic nanoparticles in thermoresponsive polymer nanocomposite films investigated by Scanning Probe and Electron Microscopy

Thin nanocomposite films have been created by spin-coating a poly(N-isopropyl acrylamide) solution containing different amounts of CoFe2O4 and Fe3O4 nanoparticles onto a substrate. These samples were investigated by Scanning Probe Microscopy and Electron Microscopy after drying at room temperature and after an additional annealing and extraction procedure to graft the polymer chemically to the substrate. It was found that during the spin-coating the particles enriched at the interface between polymer and substrate and at the polymer surface. With a sufficiently high particle concentration, a nearly closed particle layer could be obtained. Grafting and extraction of the polymers lead to a significant reduction of the polymer mass yielding a rough composite layer with a high content of embedded nanoparticles. (C) 2013 Elsevier Ltd. All rights reserved.