Vpliv površinske obdelave nanodelcev titanovega dioksida rutilne kristalne strukture na UV absorpcijske lastnosti polimernega nanokompozita : doktorska disertacija

slovenian

doktorska dela

2012

Univerza v Mariboru, Fakulteta za kemijo in kemijsko tehnologijo

Polymer composites, used in paints, are aesthetically changing the environment, in which we are living. At the same time we are using paints for surface protection, since the surface can be damaged by harmful exterier environment, for example UV light exposure. New technological solutions for improving functional properties like UV protection are in polymer composite industry introduced with the help of the nanotechnology, in this case with incorporation of TiO2 nanoparticles. Important role among the nanoparticles,used in polymer composites, have TiO2 nanoparticles. A lot of research is focused on studying properties of TiO2 nanoparticles, which enableto accomplish required functional properties and transparency of polymercomposites. TiO2 nanoparticles with rutile crystaline structure are excellent UV absorbers. For this reason they are used for incorporation in polymer composites to accomplish improved UV and weathering protection. For optimal exploitation special properties of nanoparticles in polymer compositesit is very important to prevent nanoparticles tendency to agglomeration because of London - van der Waals interactions in dispersion. This is possible to achieve by suitable nanoparticles stabilization in dispersion, which is also assured by narrow particles size distribution that consequently provides sufficient tranasparency and UV protection of polymer composite. One of the possibilities to stabilize in dispersion TiO2 nanoparticles in rutile crystaline stucture is surface treatment with inorganic and organic components. Surface treatment of rutile TiO2 nanoaprticles is imporatant for improving dispersibility and to diminish photocatalytic activity. Inorganic coating on the nanoparticles surface also increases their specific surface area when compared with untreated nanoparticles. After application of inorganic coating on TiO2 surface additional surface treatment with organic compounds is used. Treatment with surface active agent enables stabilization in solvent or polymer dispersion. The repulsion forces are being estabilshed among the particles and consequently the functional efficiency is being improved. In the presented disertation two innovative additional surface treatment procedures of TiO2 nanoparticles in rutile crystaline structure were used. We have investigated the influence of surface treatment on application properties and UV absorptionefficiency of polymer nanocomposites. For this reason we have used TiO2 nanoparticles in rutile crystaline structure synthesized with coprecipitation method. In addition to classical polydimethylsiloxane surface treatment of TiO2 nanoaprticles we have developed two additional complementarysurface treatment procedures. In order to improve nanoparticles stability in water and polymer dispersion, we have treated TiO2 nanoparticles surface with 3-glycidyloxypropyltrimethoxysilane (GLYMO) in the first and withinorganic oxide ? - Fe2O3 in the second part of our reasearch. We have studied the influence of GLYMO/TiO2 ratio and the surface treatment procedure conditions like time and temperature and the influence of wt. % of ? - Fe2O3 addition on the TiO2 nanoparticles dispersion stability. Third surface treatment procedure was perfomed on TiO2 nanoparticles of rice structure in comparison with before used spherical shape of nanoparticles. First Al2O3 was precipitated on TiO2 surface. Than we have used trisilanol polyhedral oligomeric silsesquioxanes (POSS) for additional surface treatment of TiO2 nanoparticles. We have studied the influence of TiO2 surface treatment with POSS on transparency and UV efficiency of polymer nanocomposite. With additional surface treatment of TiO2 nanoparticles in rutile crystaline structure we have confirmed our hypotheses about the surface treatment influence on UV absorption properties as well as on the transparency of polymer composite.

07.08.2023