Influence of Structure and Organic‐Inorganic Phase Interactions on Coating Mechanical Properties in the Ternary Goethite:Poly(HEMA):Silica System

Abstract

AbstractThe trapping of nanoparticles inside a hybrid matrix is of great importance for the design of flexible devices with good mechanical properties and for the manipulation of nanoparticles whilst avoiding the use of nanopowders. In this work, transparent coloured coatings on glass were prepared by incorporating Goethite nanorods in a silica:PHEMA [poly(hydroxyethyl methacrylate)] hybrid matrix. Results show that incorporation of Goethite with a volume content higher than 27 % leads to the formation of a porous structure through a phase separation mechanism which induces a dramatic collapse of the mechanical properties. When the Goethite volume content is below 16 %, the mechanical properties of the coating are governed by the interactions between organic and inorganic domains. Goethite interacts preferentially with the silica network through the formation of hydrogen bonds and no direct interactions with PHEMA were observed. In the absence of strong covalent bonds between the silica:PHEMA hybrid and the nanoparticles, Goethite nanorods do not provide any mechanical strengthening. As a result, interpenetration between silica and PHEMA networks enables fine tuning of the final mechanical properties with the coating silica content.