Polyhedral oligomeric silsesquioxanes as titanium dioxide surface modifiers for transparent acrylic UV blocking hybrid coating

Architectural coatings are often recommended to enhance the durability of wood in exterior environment however the coatings itself are not UV stable enough for long term protection. For this reason inorganic UV absorbers like nano TiO2 in rutile crystal form are of great research interest in last decade. It's advantage is UV reversible absorption activity in polymer composite like coating during weathering [1]. On the other side the TiO2 surface has limited compatibility with polymers what can result in non-stable dispersion. To achieve a better compatibility between nano-particles and polymer matrix in coating, the use of different inorganic/organic surface modification of TiO2 rutile nano-particles is recommended. In order to improve dispersability of TiO2 rutile nano-particles in acrylic water based coating, two step surface modification of TiO2 nano-particles was investigated. First, TiO2 nano-particle's surface was modified with Al2O3 and second polyhedral oligomeric silsesquioxanes (POSS) were used in order to improve TiO2 dispersability and to enable higher UV absorption by reduction of nanoparticles agglomeration. Evaluation of physical properties before and after exposed weathering tests of coating samples with surface modified TiO2 rutile nano-particles proved our prediction. The results can be used for further optimization of nano-composites in coating applications for long term UV protection. (C) 2011 Elsevier BM. All rights reserved.