Organic coatings are frequently applied to metals, often in circumstances where there is a need to protect the substrate from corrosion or to improve the aesthetic quality of a product. Increasingly, coatings are also expected to provide additional functionality, such as anti-bacterial properties. Concurrent with the need to satisfy ever more demanding specifications, coating formulators are being obliged to comply with stringent environmental legislation. A research area which may benefit the development of coating formulations is that of nanocomposite synthesis, in which the composite additives have at least one dimension in the nanometre size range. The current research has sought to modify a waterborne organic coating primer with two types of nano-sized additives: layered clays and titanium dioxide nanoparticles. Dispersion of the particles at loadings up to 5% w/w was achieved by ball milling and the modified coatings were subjected to numerous tests to ascertain the effect of the additives. Titanium dioxide was found to improve the tribological properties and corrosion resistance of the coatings, while the addition of magnesium aluminium hydroxycarbonate (hydrotalcite) layered clay had a deleterious effect. Some coatings exhibited a cracked morphology, although no correlation between particle loading and the presence of cracks could be determined. A preliminary investigation into substrate preparation was also conducted. This ensured that the degree of cleanliness of the hot-dip galvanized substrates was both satisfactory and consistent.

Increasing use of engineered nanomaterials presents concerns as some nanoparticles appear to be harmful to both human health and the environment. Effective treatment methods are required to remove problematic nanoparticles from (waste)water streams. Porous media filtration, commonly used for the removal of particulate matter, shows promise for nanoparticle treatment. The goal of this work is to investigate the potential of porous media filtration for the abatement of nanoparticles from aqueous waste streams. To this end, an automated method was developed that allows real-time and in-situ monitoring of nanoparticle transport and retention in porous media using online measurement of UV-visible absorbance or fluorescence. Development of fluorescent-core nano-silica (n-SiO₂) in controllable sizes provided an excellent tracer for nanoparticle transport in porous media. Measurement of n-SiO₂ by destructive techniques is complicated by high natural Si background levels. Fluorescence monitoring enables real-time measurement, facilitating rapid evaluation of n-SiO₂ transport. Synthesized n-SiO₂ remain in their primary sizes making an evaluation of the behavioral change of particles due to transition into the "nano" range possible. A comparison of the role of particle size on transport in porous media displayed the importance of particle number concentration as the dominance of site-specific adsorption may be obscured by simple mass concentration evaluation.T he effectiveness of different bed materials, namely, sand, activated carbon (AC), and diatomaceous earth (DE), for the removal of TiO₂ nanoparticles (n-TiO₂) from aqueous streams was investigated. DE proved promising for n-TiO₂ capture shown by its high bed capacity (33.8 mg TiO₂ g⁻¹(medium)) compared to AC (0.23 mg TiO₂ g⁻¹(medium)) or sand (0.004 mg TiO₂ g⁻¹(medium)). The presence of organic and synthetic contaminants produced varying effects on n-TiO₂ retention, mostly due to either enhanced electrostatic or steric interactions. Application of a process simulator combining physical straining with site-specific interactions, delineating physisorption from chemisorption and diffusion limited interactions, enabled the accurate fit of n-TiO₂ transport in sand, AC and DE. The fitting process revealed the advantage of DE due to increased physisorption and physical straining of n-TiO₂. Modeling of this system afforded the elucidation of controlling retention mechanisms and provides a basis for future scaling and system design.

Device associated infections are a growing problem in the field of orthopaedics and dentistry. Bacteria adhering to implant surfaces and subsequent biofilm formation are challenging to treat with systemic administered antibiotics. Functionalization of implant surfaces with therapeutic coatings that are capable of inhibiting bacterial adhesion are therefore considered as a straight forward strategy to treat and prevent implant related infections. In this thesis, the use of crystalline, arc deposited TiO2 and biomimetic hydroxyapatite (HA) coatings were evaluated with respect to their potential as antibacterial surface modifications for bone-anchored implants. UV light induced photocatalysis of anatase dominated TiO2 coated surfaces was shown to provide a bactericidal effect against S. epidermidis under clinically relevant illumination times and doses. Major parts of the drug release work carried out was based on biomimetic HA (HA-B) coated fixation pins. The analysis of the coating characteristics revealed that the nanoporous structure of HA-B coatings in addition to the chemical composition and surface charge are essential parameters that influence the drug carrier performance. Loading by adsorption was demonstrated to be a feasible approach to quickly incorporate antibiotics. The controlled release of antibiotics was shown to facilitate bactericidal effects against S. aureus over application-relevant time periods, even when exposed to biomechanical forces during insertion into bone model materials. Antibiotic incorporation during coating growth was shown to promote somewhat longer drug release time periods than those obtained using adsorption loading. In summary, functionalization of implant surfaces with bioactive and biocompatible coatings is a promising concept to impact the clinical success for bone-anchored applications. The additional feature of optional, on-demand antibacterial properties of these coatings through either on-site drug release or photocatalytic antibacterial treatment is advantageous for the prevention and effective treatment of devices-associated infections. Both strategies provide an immediate response to the implant contamination by bacteria and are believed to contribute towards minimizing the origin of post-surgical infections, while at the same time improving the interfacial stability between implant and bone.

The wide use of nanoscale materials in food and health care products raises the concern of their possible uptake across the gastrointestinal tract, but very limited data are available on their uptake kinetics, and the potential hazards for humans. In this study, the uptake mechanism of titanium dioxide (TiO2) across the isolated perfused fish intestine and human intestinal Caco-2 cells were evaluated. The in vitro preparation of the whole gut sac and the isolated perfused intestine of rainbow trout were performed using both bulk and nano TiO2 in a concentration of 1 mg l-1 for up to 4 h. The results showed that the Ti from both bulk and TiO2 NPs were mainly accumulated in the mid and hind intestine, with 80% or more of the accumulation in the mucosa rather than the underlying muscularis. Perfused intestines showed a saturable, time-dependent accumulation of the Ti from TiO2 and the uptake of Ti from exposure to NPs was faster than that of the bulk form. The uptake of Ti from exposure to TiO2 NPs increases 10 fold when the CO2 in the gas mixture was lowered to 0.5%. Subsequently, further investigation on the mechanisms of uptake of TiO2 was applied using different kinds of inhibitors. Adding 10 mmol l-1 cyanide did not stop Ti uptake from TiO2 exposures, and 100 µmol l-1 vanadate (ATPase inhibitor) caused a 2.8 fold reduction in the net uptake rate of Ti for the TiO2 NP exposure. Luminal additions of 120 IU ml-1 nystatin (endocytosis inhibitor) blocked the uptake of Ti from both bulk and TiO2 NPs treatments. The results indicate that Ti accumulation from TiO2 exposures was sensitive to both nystatin and vanadate; the former suggesting that there is an endocytosis involvement in the uptake of TiO2 across the intestinal epithelium. Human intestinal Caco-2 cell showed a steady, saturable and time-dependent accumulation of Ti over 24 h exposures to 1 mg l-1 TiO2 (for all forms of TiO2). A scanning electron microscope study indicated the appearance of the particles underneath the cells, increasing the evidence of the Ti uptake from different forms of TiO2 by Caco-2 cells. Both nystatin and vanadate increase the accumulation of TiO2 which suggests interference of these drugs with endocytic pathways. All the data in the thesis demonstrates Ti uptake across the intestinal epithelium from TiO2 exposures involving CO2-dependent and nystatin-sensitive mechanisms. The results in this thesis have contributed to some understanding on the behaviour, uptake and effects of the TiO2 NPs across the intestine; and highlight the possible dietary hazard of the NPs to human health.

Nanotechnology is a rapidly growing industry of global economic importance, with new technologies exploiting the novel characteristics of materials manufactured at the nanoscale being developed for use within the biomedical, electronic, energy production and environmental sectors. The unusual properties of engineered nanomaterials (ENMs) that make them useful in such applications have led to concerns regarding their potential impact on the environment. The aquatic environment is particularly at risk of exposure to ENPs, yet, there is currently little known about their behaviour in aquatic systems, their capacity to be taken up by aquatic organisms or their potential toxic effects. The studies that were conducted during this work sought to investigate the ecotoxicology of a range of metal and metal oxide nanoparticles using fish as a vertebrate model. In order to gain a better understanding of the uptake and effects of ENMs in fish, rainbow trout (Oncorhynchus mykiss) were exposed to nanoparticulate (34 nm) and bulk (>100 nm) titanium dioxide particles via the water column (500 and 5000 µg L-1), and to titanium dioxide nanoparticles via the diet (0.1 and 1 mg g-1 food) and via intravenous injection (1.3 mg kg-1 body weight). Uptake of titanium dioxide into the tissues of trout after waterborne and dietary exposure was found to be very low, suggesting limited bioavailability of the nanoparticles to the fish, although small amounts of uptake of titanium dioxide across the gill epithelial membrane were observed using coherent anti-stokes Raman scattering. Intravenously injected titanium dioxide accumulated and was retained in the kidneys for up to 21 days, but no adverse effect on kidney function was detected. Silver nanoparticles are already in widespread use in a variety of consumer products such as wound dressings, food containers, sock fabrics and paints, principally for their antimicrobial activity. Despite its growing commercialisation, there is little known about the environmental effects of the use of nanoparticulate silver in these products. In order to investigate these potential effects, rainbow trout were also exposed to 10 nm, 35 nm and bulk (0.6-1.6 µm) silver particles via the water column at concentration of 10 and 100 µg L-1. Uptake of silver in the gills and liver of trout occurred, with smaller nanoparticles showing a greater propensity for association with gill tissue, but with no significant differences in uptake between particles of different sizes in the liver. No increases in lipid peroxidation were detected in gills, liver or blood plasma of trout, however, expression of cyp1a2 was significantly up-regulated in exposures to 10 nm silver particles in the gill, suggesting an increase in oxidative metabolism. In an attempt to develop an effective high through-put in vitro screening assay for ENMs, the suitability of isolated rainbow trout primary hepatocytes was examined as a potential model for in vitro screening of a range of toxicological endpoints in response to nanoparticles and for studying uptake of nanoparticles into cells. The hepatocytes retained a good level of functionality after culturing as evidenced by vitellogenin production in response to the synthetic oestrogen, 17β-oestradiol. The cultured hepatocytes, however, showed limited responses on exposure to titanium dioxide, zinc oxide, cerium oxide and silver nanoparticles for lipid peroxidation and glutathione-s-transferase activity assays. Furthermore, the hepatocytes were unresponsive to the induction of these biological responses in the positive controls, suggesting they are not a good model for investigating the potential toxic effects of ENMs in terms of these endpoints. Uptake of the nanoparticles into the cells, however, was demonstrated by coherent anti-stokes Raman spectroscopy, indicating that this in vitro assay may provide a useful model for studying uptake of ENPs into cells. The studies conducted in this thesis contribute the science base regarding the bioavailability of ENPs in aquatic media as well as highlighting the importance of characterisation of ENPs in understanding their behaviour, uptake and effects in aquatic systems and in fish.

D.Phil. / Clean water (i.e. water that is free of toxic chemicals and pathogens) is essential to human health and in South Africa the demand is fast exceeding the supply. The prevalence of toxic contaminants in water remains a huge challenge for water supplying companies and municipalities. However, the presently used water treatment technologies either fail to remove these contaminants to acceptable levels or they transform them into more toxic substances (e.g., DBPs). Nanocatalysts, especially TiO2 (titania) have a proven potential to treat ‘difficult-to-remove’ contaminants and hence are expected to play an important role in solving many serious environmental and pollution challenges. In this study TiO2 nanocatalysts were used for the degradation of Rhodamine B dye both under UV and visible light irradiation. Two phases of titania, i.e. anatase and rutile phases, were compared for the degradation of Rhodamine B under UV light irradiation. The anatase titania was found to be more photocatalytically active for the degradation of Rhodamine B than the rutile phase. It completely degraded 100 mg ℓ–1 (100 mℓ) of Rhodamine B within 270 min and was two times more photocatalytically active than the rutile phase (Kapp of 0.017 min–1 compared to 0.0089 min–1). To extend the band edge of the titania nanocatalysts towards visible-light, TiO2 was doped with metal ions (Ag, Co, Ni and Pd). These metal-ion-doped titania nanocatalysts were photocatalytically active under visible-light illumination. The Pd-doped titania had the highest photodegradation efficiencies, followed by Ag-doped and Co-doped, while Ni-doped had the lowest. The optimum metal-ion loading percentage was found to be at 0.4%, with the exception of Co-doped titania as it had the highest efficiencies at 1% loadings. The free and metal-ion-doped titania nanocatalysts were embedded on carbon-covered alumina (CCA) supports. The CCA-supported TiO2 nanocatalysts were more photocatalytically active under visible light illumination than they were under UV-light irradiation. The CCA-supported metal-ion-doped titania nanocatalysts were more photocatalytically active under visible light than their unsupported counterparts. The CCA-supported Pd-TiO2 nanocatalysts were the most active while CCA-supported Ni-TiO2 catalysts were the least active. The improved photocatalytic activities observed were as a result of increased surface areas of the CCA-supported nanocatalysts. Also, supporting the nanocatalysts did not destroy the anatase phase of the titania while doping with metal ions and supporting on CCAs resulted in decreased band gap energies, hence the visible-light photocatalytic activities. Finally, the metal-ion-doped titania nanocatalysts were supported on glass slides using the layer-by-layer thin film self-assembly technique. This was to overcome the aggregation and post treatment problems associated with the use of TiO2 in suspension form. PAH and PSS were the polyelectrolytes used. These metal-ion-doped titania thin films were highly porous and strongly adhered by the polyelectrolytes onto the glass slides. The thin films were photocatalytically active for the degradation of Rhodamine B under visible light irradiation. The photocatalytic degradation efficiencies observed were similar for all four metal-ions (i.e. Ag, Co, Ni and Pd) with average degradation of 30%, 50%, 70% and 90% for 5 catalysts (5 glass slides) of 1, 3, 5 and 10 bi-layers, respectively, after 330 min. Although, these were less active than the suspended titania nanocatalysts, this study proved as a stepping stone towards large scale use of titania nanocatalysts using solar energy as the irradiation source. Also, catalyst reusability studies were performed and the PAH/PSS m-TiO2 thin films were found to be highly stable over the five cycles it was tested for.

<p>The ability of photocatalytic nanoparticles (NPs) to produce reactive oxygen species (ROS) has inspired research into several new applications and technologies, including water purification, contaminant remediation, and self-cleaning surface coatings. As a result, NPs continue to be incorporated into a wide variety of increasingly complex products. With the increased use of NPs and nano-enabled products and their subsequent disposal, NPs will make their way into the environment. Currently, many unanswered questions remain concerning how changes to the NP surface chemistry that occur in natural waters will impact reactivity. This work seeks to investigate potential influences on photoreactivity – specifically the impact of functionalization, the influence of anions, and interactions with biological objects - so that ROS generation in natural aquatic environments may be better understood.</p><p>To this aim, titanium dioxide nanoparticles (TiO2) and fullerene nanoparticles (FNPs) were studied in terms of their reactive endpoints: ROS generation measured through the use of fluorescent or spectroscopic probe compounds, virus and bacterial inactivation, and contaminant degradation. Physical characterization of NPs included light scattering, electron microscopy and electrophoretic mobility. These systematic investigations into the effect of functionalization, sorption, and aggregation on NP aggregate structure, size, and reactivity improve our understanding of trends that impact nanoparticle reactivity.</p><p>Engineered functionalization of FNPs was shown to impact NP aggregation, ROS generation, and viral affinity. Fullerene cage derivatization can lead to a greater affinity for the aqueous phase, smaller mean aggregate size, and a more open aggregate structure, favoring greater rates of ROS production. At the same time however, fullerene derivatization also decreases the 1O2 quantum yield and may either increase or decrease the affinity for a biological surface. These results suggest that the biological impact of fullerenes will be influenced by changes in the type of surface functionalization and extent of cage derivatization, potentially increasing the ROS generation rate and facilitating closer association with biological targets.</p><p>Investigations into anion sorption onto the surface of TiO2 indicate that reactivity will be strongly influenced by the waters they are introduced into. The type and concentration of anion impacted both aggregate state and reactivity to varying degrees. Specific interactions due to inner sphere ligand exchange with phosphate and carbonate have been shown to stabilize NPs. As a result, waters containing chloride or nitrate may have little impact on inherent reactivity but will reduce NP transport via aggregation, while waters containing even low levels of phosphate and carbonate may decrease “acute” reactivity but stabilize NPs such that their lifetime in the water column is increased.</p><p>Finally, ROS delivery in a multicomponent system was studied under the paradigm of pesticide degradation. The presence of bacteria or chlorpyrifos in solution significantly decreased bulk ROS measurements, with almost no OH detected when both were present. However, the presence of bacteria had no observable impact on the rate of chlorpyrifos degradation, nor chlorpyrifos on bacterial inactivation. These results imply that investigating reactivity in simplified systems may significantly over or underestimate photocatalytic efficiency in realistic environments, depending on the surface affinity of a given target.</p><p>This dissertation demonstrates that the reactivity of a system is largely determined by NP surface chemistry. Altering the NP surface, either intentionally or incidentally, produces significant changes in reactivity and aggregate characteristics. Additionally, the photocatalytic impact of the ROS generated by a NP depends on the characteristics of potential targets as well as on the characteristics of the NP itself. These are complicating factors, and the myriad potential exposure conditions, endpoints, and environmental systems to be considered for even a single NP highlight the need for functional assays that employ environmentally relevant conditions if risk assessments for engineered NPs are to be made in a timely fashion so as not to be outpaced by, or impede, technological advances.</p> / Dissertation

The adsorption of methylene blue onto two types of commercial activated carbons, a mesoporous type (Norit CA1) and microporous type (207C) was analysed. Powdered TiO2 was mixed with the carbon and added to the dye solution to determine the influence of the photocatalyst during the adsorption process. Equilibrium and kinetics experiments were done with and without any addition of photocatalytic titanium dioxide (TiO2). Changes in capacity, heterogeneity, and heat of adsorption were detected and related to changes in the quantity of TiO2 added by evaluating the equilibrium parameter from 13 isotherm models. The influence of TiO2 on the adsorption kinetics of the dye was correlated using simplified kinetic-type model as well as mass transfer parameters. Using a formal design of experiments approach responses such as the removal of the dye, variation of pH, external mass transfer rate (KF) and intraparticle rate constant (Ki) were evaluated. Results indicated that TiO2 increased the uptake of methylene blue onto CA1, increased Ki and CA1-TiO2 interactions had electrostatic nature. In contrast, TiO2 was seen to inhibit the equilibrium adsorption for 207C by reducing its capacity. The 207C-TiO2 interaction was attributed to a specific adsorption of TiO2 on the coconut-based adsorbent, as zeta potential and pH measurements seemed to suggest. The regeneration of activated carbon using UV-C/TiO2 heterogeneous photocatalysis in a novel bell photocatalytic reactor, and in a standard-type coiled-tube photoreactor was also studied. Initially, response surface methodology was applied to finding the optimum conditions for the mineralization of methylene blue in both reactors using methylene blue as model compound and TiO2 as photocatalyst performing direct photocatalytic decolourization. Methylene blue concentration, TiO2 concentration and pH were the variables under study. Complete mineralization of the dye was achieved in the coiled-tube reactor using 3.07 mg/L of methylene blue at pH 6.5 with 0.4149 g/L TiO2. The regeneration experiments in the coiled-tube photoreactor were done using One Variable at Time (OVAT) method. The effect of the mass of TiO2 was the only studied variable. The study indicated an increase in regeneration of CA1 and a decrease in the pH during the oxidation step at higher concentration of the photocatalyst. In the case of the regeneration of 207C, the addition of TiO2 lowered the regeneration and made the suspension more basic during the photocatalytic step. However these results were not statistically significant. Experiments using the bell photoreactor were performed applying the same response surface method used in direct photocatalytic decolourization (control). The variables under study were pH, concentration of dye-saturated carbon and TiO2 concentration. The regeneration percentage was the chosen response. Low regeneration percentages were achieved (maximum 63%), and significant differences (95% confidence interval) were found between the regeneration of the activated carbons, being higher in the case of powdered CA1 as compared with granular 207C.

Orientador: José Humberto Dias da Silva / Coorientador: Paulo Noronha Lisboa Filho / Banca: Valmor Roberto Mastelaro / Banca: Wido Herwig Schreiner / Banca: Francisco Eduardo Contijo Guimarães / Banca: Antonio Ricardo Zanata / Resumo: A busca por um melhor entendimento da inter-relação entre os parâmetros envolvidos no processo de crescimento de filmes de dióxido de titânio (Tio2) e as propriedades estruturais, eletrônicas e magnéticas resultantes foi a principal motivação deste trabalho. Para isso, filmes Ti)2 foram crescidos usando a técnica de RF magnetron sputtering em diferentes condições. Um primeiro conjunto de filmes de Ti)2 não dopados foi depositado com fluxo contínuo de O2. Em outro conjunto, utilizou-se sistemáticas interrupções no fluxo de O2 durante a deposição. O último grupo de amostras foi depositado usando fluxo contínuo O2 e dopagem com Mn. Os filmes do primeiro grupo apresentaram morfologia colunar com estrutura majoritariamente anatase e com gap óptico de ~3,3 eV, independente da temperatura dos substratos (450ºC e 600ºC) e da razão Ar/O2 utilizada. A diminuição do fluxo de O2 provocou um aumento da absorção sub-gap que foi associada a um aumento dos defeitos eletrônicos no material. Um tratamento térmico em vácuo a 800ºC, realizado sobre filmes de TiO2 puros, revelou um aumento da fração rutila e da absorção óptica, o que também foi associado a um aumento da concentração de defeitos eletrônicos. A análise dos filmes onde o fluxo de oxigênio foi sistematicamente interrompido durante a deposição mostrou que o aumento no número de interrupções não interferiu significativamente na morfologia colunar dos filmes, mas produziu um considerável aumento na fração rutila dos filmes, bem como um aumento na absorção óptica sub-gap. O aumento na absorção na região do visível e infravermelho próximo foi atribuído a um aumento na concentração de defeitos que, de acordo com cálculos baseados na teoria do funcional da densidade, estão relacionados a estados de energia provenientes de vacâncias de oxigênio. Os filmes de TiO2 dopados com diferentes concentrações de Mn pertencentes ao terceiro grupo também / Abstract: The search for a better understanding of the interrelation between the parameters involved in the process of film growth and the resulting structural, electronic and magnetic properties was the main motivation of this work. To the purpose, TiO2 films were grown by RF magnetron sputtering technique in different conditions. In a first set, TiO2 films were deposited with continuous O2 flow. In another set, systematic interruptions in the O2 flow were performed during the deposition. The last group of samples was deposited using a continuous O2 flow and Mn doping. A detailed analysis of the first group showed that these films exhibit columnar morphology with mainly anatase structure and optical gap of ~3.3eV, independent of the substrate temperature (450ºC and 600ºC) and the ratio used. THe decrease in O2 flux caused an increase in the sug gap absorption which associated with the increase in electronic defects of the material. Anneling in vacuum at 800ºC performed on pure TiO2 films showed an increase in the rutilo fraction, a red shift of the optical absorption edge, and an increase of the sub gap absorption associated with the increase of the electronic defects. The analysis of the films were the O2 flow was systematically interrupted during the deposition showed that the increase in the number of interruptions did not interfere significantly in the columnar morphology, but produced a significant increase in the fraction of rutile and brookite as well as an increase in sub-gap absorption. The increase in absorption in the visible and near infrared was attributable to an increase in the concentration of defects that, according to calculations based on the density functional theory, should be related to energy states provides by O vacancies. The Mn doped films also present a compact columnar morphology and a strong and systematic favoring of the rutile... (Complete abstract click electronic access below) / Doutor

Nesse estudo procurou-se avaliar o impacto do aditivo dióxido de titânio, mistura anatase-rutila, no comportamento fotocrômico de nanocompósitos baseados em materiais híbridos do tipo silicatos orgânicos (Ormosis) contendo ácido fosfotúngstico, \'H IND.3\'PW IND.12\'O IND.40\'. O material híbrido foi obtido via processo sol-gel tendo sido caracterizado quanto à sua morfologia por Microscopia óptica e Microscopia Eletrônica de Varredura (MEV), que mostrou que os filmes em geral são pouco rugosos e homogêneos. Estudos de Espectroscopia Vibracional (Espectroscopia de Absorção na Região do Infravermelho e Raman) confirmaram a integridade do heteropoliânion fosfotungstato e a formação de uma rede tridimensional de silicatos, assim como, permitiram identificar a abertura do anel oxirano para formar um poli(óxido de etileno) ramificado, caracterizando a formação de um material híbrido classe II. A Espectroscopia de absorção na região do Ultra-violeta visível (UV-vis) ou espectroscopia eletrônica, além de confirmar a integridade química da espécie fosfotungstato, permitiu acompanhar a formação de heteropoliazuis mono- e duplamente reduzidos de maneira quantitativa. A cristalinidade dos materiais foi avaliada por Difração de raios-x (DRX) e mostrando que o sólido resultante é amorfo. Os estudos espectroscópicos permitiram inferir que a interação entre os polioxometalatos e as nanopartículas de \'TI\'O IND.2\' deve ser fraca, entretanto, estudos posteriores são necessários para confirmar isto. A adição de nanopartículas leva a um material mais sensível à radiação UV, entretanto, não há uma correlação linear entre massa de nanopartículas adicionada e variação de absorbância devido à irradiação. / In this study we evaluated the impact of the additive titanium dioxide, anatase-rutile mixture, Photochromic behavior of nanocomposite materials based on hybrid organic-type silicates (Ormosia) containing phosphotungstic acid, \'H IND.3\'PW IND.12\'O IND.40\'. The hybrid material was obtained via sol-gel process has been characterized for their morphology by optical microscopy and scanning electron microscopy (SEM), which showed that the films are often little rough and smooth. Studies of Vibrational Spectroscopy (Absorption Spectroscopy in the infrared and Raman) confirmed the integrity of phosphotungstic acid and the formation of a three-dimensional network of silicates, as well as the opening of the oxirane ring to form a poly (ethylene oxide) branched characterizing the formation of a hybrid class II material. The absorption spectroscopy in the region of Ultra-violet visible (UV-vis) to confirm the chemical integrity of phosphotungstate species, allowed us to track the formation of mono-and doubly heteropolyblues reduced quantitatively. The crystallinity of the materials was evaluated by x-ray diffraction (XRD) and showed us that the resulting solid is amorphous. The spectroscopic studies allowed us to infer that the interaction between polyoxometalates and \'TI\'O IND.2\' nanoparticles should be weak, however, further studies are needed to confirm this. The addition of nanoparticles leads to a material more sensitive to UV radiation, however, there is not a linear correlation between mass of nanoparticles added and absorbance variation due to irradiation.