Doutorado em Química
URI Permanente para esta coleção
Nível: início
Ano de início: 2014
Conceito atual na CAPES: 5
Ato normativo: Homologação da 85ª Reunião do CTC-ES, Parecer CNE/CES nº 163/2005.
Processo nº 23001.000081/2005-56 do Ministério da Educação.
Publicado no DOU 28/07/2005, seção 1, página 11)
Periodicidade de seleção: Anual
Área(s) de concentração: Química
Url do curso: https://quimica.vitoria.ufes.br/pt-br/pos-graduacao/PPGQ/detalhes-do-curso?id=956/a>
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- ItemMatriz polimérica biocompatível contendo nanopartículas de prata para aplicação como base em esmalte de unha(Universidade Federal do Espírito Santo, 2024-12-19) Paula, Aislana Cole de; Silva Filho, Eloi Alves da; https://orcid.org/0000-0002-9306-7882; http://lattes.cnpq.br/8259708288584235; Luz, Priscilla Paiva; https://orcid.org/0000-0002-9460-546X; http://lattes.cnpq.br/3663470249824660; https://orcid.org/0009-0004-4865-668X; http://lattes.cnpq.br/3806442581478422; Loureiro, Felipe Augusto Moro; https://orcid.org/0000-0002-0524-1423; http://lattes.cnpq.br/1354971719304565; Domingos, Eloilson; https://orcid.org/0000-0002-7479-2691; http://lattes.cnpq.br/5519453382330308 ; Dalmaschio, Cleocir José; https://orcid.org/0000-0002-3773-5786; http://lattes.cnpq.br/5209978120430790; Machado, Marta Alburqueque; https://orcid.org/0000-0001-8335-3351; http://lattes.cnpq.br/5991893415892784Nitrocellulose has played a fundamental role in the development of nail polishes since the 1920s, establishing itself as a film-forming polymer. However, due to its high glass transition temperature, the use of resins and plasticizers became necessary to improve the flexibility and adhesion of the film. Since the 1940s, these additives have been associated with toxic and sensitizing effects, driving the search for safer and more sustainable alternatives, a challenge that remains in 2024. This study proposed the replacement of these additives with poly(ε-caprolactone) and polyethylene glycol, biocompatible and biodegradable polymers with plasticizing potential, whose combined application with nitrocellulose had not yet been explored. Poly(ε-caprolactone) was also investigated as a thermoplastic resin, given its ability to form films in association with nitrocellulose. Four experimental formulations of transparent nail polish bases (Bases 1A, 1B, 2A, and 2B), were developed and compared to a sample of pure nitrocellulose and to a commercial hypoallergenic base (Base C). The formulations were evaluated for water resistance, wettability, and cytotoxicity, showing comparable or superior performance to Base C, particularly in biocompatibility assays, where lower cytotoxicity indices were observed. The interaction and miscibility between the polymers were confirmed by dynamic mechanical analysis, which demonstrated a significant reduction in glass transition temperature, ranging from 30.5 °C to 40.0 °C, compared to pure nitrocellulose (107.5 °C) and Base C (34.0 °C), evidencing the plasticizing effect of poly(ε-caprolactone) and polyethylene glycol. Miscibility was also corroborated by X-ray diffraction, scanning electron microscopy, and refractive index analysis. Considering the therapeutic potential of nail polishes as delivery vehicles for active substances, silver nanoparticles were synthesized in situ in Bases 1B and 2B, selected based on the best results obtained in the preliminary assays. Nanoparticles formation was confirmed by the color change of the solutions, which acquired yellowish tones, and by the presence of characteristic absorption bands in the 444–448 nm region, detected by UV-Vis spectroscopy. Transmission electron microscopy revealed predominantly spherical nanoparticles with sizes ranging from 5 to 50 nm. The results demonstrate the potential of combining poly(ε-caprolactone) and polyethylene glycol as safe and effective alternatives to traditional plasticizers and resins in nail polish formulations, contributing to the development of less toxic products with improved functional properties and promising prospects for innovative therapeutic applications in the treatment of nail disorders.
- ItemEstudo por dinâmica molecular de oligômeros e polímeros de PET, PP e PCL para obtenção de propriedades físico químicas(Universidade Federal do Espírito Santo, 2024-04-11) Uliana, Fabricio; Gonçalves, Arlan da Silva; https://orcid.org/0000-0002-5965-3191; http://lattes.cnpq.br/4139608457982550; Silva Filho, Eloi Alves da; https://orcid.org/0000-0002-9306-7882; http://lattes.cnpq.br/8259708288584235; https://orcid.org/0000-0001-5591-3403; http://lattes.cnpq.br/5044813442764534; Guizado, Teobaldo Ricardo Cuya; https://orcid.org/0000-0002-3908-8076; http://lattes.cnpq.br/8371827192990091; Prado, Adilson Ribeiro; https://orcid.org/0000-0001-8808-4488; http://lattes.cnpq.br/3085491325255749; Melo, Carlos Vital Paixão de; http://lattes.cnpq.br/9555951916049288; Machado, Marta Albuquerque; https://orcid.org/0000-0001-8335-3351; http://lattes.cnpq.br/5991893415892784This work seeks to obtain data regarding the thermal behavior of some of the main polymers used. For this, it was necessary to develop software that assists in the creation of polymeric systems with a mass greater than 10000 g∙mol-1 parameterized with the OPLS-AA force field. This software was developed using the C++ language with a graphical interface built using the QT framework and was named FPolymer. The polymeric models generated by the developed program were submitted to a molecular dynamics calculation protocol. The structures of the polymers undergo stages of energy minimization using different algorithms followed by molecular dynamics in vacuum for 10 ns so that the packing of the structures occurs. This process is carried out in quintuplicates generating five distinct structures that are submitted to dynamics of 100 ns for structural equilibration and then, dynamics of 100 ns with heating ramp are performed. With this procedure, it is possible to obtain data such as volume variation, density, radius of gyration, coulomb energy, among others, as a function of temperature and with this it was possible to identify properties such as density, melting point and transition temperature for the polymers PET, PP and PCL. The values obtained are within the ranges of the values obtained experimentally showing that both the created models and the proposed calculation protocol are efficient for carrying out computational studies of these polymers enabling the realization of several future studies including even the formation of blends and obtaining their properties.
- ItemAvaliação dos efeitos da foto-oxidação de petróleos derramados em regiões de clima tropical à partir de uma simulação em escala laboratorial(Universidade Federal do Espírito Santo, 2025-07-21) Côgo, Sannya Maria Britto; Castro, Eustáquio Vinicius Ribeiro de; https://orcid.org/0000-0002-7888-8076; http://lattes.cnpq.br/1055263403980509 ; https://orcid.org/0000-0002-3702-196X; http://lattes.cnpq.br/5921527094829519 ; Cunha Neto, Álvaro; https://orcid.org/0000-0002-1814-6214; http://lattes.cnpq.br/7448379486432052; Dalmaschio, Cleocir José; https://orcid.org/0000-0002-3773-5786; http://lattes.cnpq.br/5209978120430790; Gallotta, Fabiana Dias Costa; https://orcid.org/0000-0002-5680-1080; http://lattes.cnpq.br/3255525478766474; Martins, Laércio Lopes; https://orcid.org/0000-0001-6216-990X; http://lattes.cnpq.br/9943766587624020Oil spills at sea, such as those involving the Exxon Valdez (1989), the Gulf War (1991) and the Deepwater Horizon (2011), as well as the recent appearance of oil on beaches along the Brazilian coast (2019), have significant environmental and socio-economic impacts. Following a spill, the oil undergoes weathering processes involving physical, chemical, and biological transformations that alter its properties. Evaporation and photo oxidation play a key role in modifying the oil's chemical composition, especially in tropical regions with high levels of solar radiation. Photo-oxidation is the result of the interaction between ultraviolet (UV) radiation and oxygen. This process promotes the formation of oxygenated compounds and polyaromatic hydrocarbons, which can increase environmental toxicity and complicate remediation processes. This study investigated the physicochemical and compositional changes in five samples of Brazilian offshore oil subjected to weathering by evaporation and photo-oxidation under simulated tropical conditions. Initially, the samples were distilled at over 250°C+ at the top of the column to simulate evaporation. The evaporated samples were then exposed to ultraviolet radiation in an acrylic box for 219 days, with samples collected on days 7, 58, 107, 164 and 219 to assess photochemical weathering progression over time. Physico-chemical analyses were carried out on the frescode and evaporated oil samples, including the following properties: API grade; density; kinematic and dynamic viscosities; pour point; total sulphur content; asphaltene content; total acid number (TAN); and salinity index. Spectroscopy in the mid-infrared region (FTIR) revealed a decrease in similarity and structural changes between the oils in the assemblies throughout the weathering process. The saturated and aromatic fractions were analysed using gas chromatography coupled to mass spectrometry (GC-MS) through saturated, aromatic, and polar (SAP) fractionation, which allowed individual compounds to be identified, and their changes assessed throughout the simulation. The results revealed significant losses of the most volatile compounds following evaporation, as well as changes in the physicochemical properties and resistance of saturated biomarkers, even after prolonged exposure to UV radiation. An increase in the baseline was observed in the aromatic fractions from day 7 onwards, which was associated with the formation of an unresolved complex mixture (UCM). Ratios of aromatic compounds such as 2-methylnaphthalene/phenanthrene and nalkylbenzenes proved sensitive to changes caused by sunlight exposure. ¹H nuclear magnetic resonance analyses corroborated the high-resolution mass spectrometry (ESI(+)-Orbitrap-MS) data, which indicated a progressive increase in oxygenated and nitrogenated compounds that were possibly formed by photochemical oxidation. This study highlights the importance of evaporation and photochemical oxidation processes in the chemical transformation of oil in tropical environments. It provides relevant information for improving environmental emergency response strategies and contingency plans in the event of oil spills at sea.
- ItemFormulação de fluidos de perfuração à base água a partir do rejeito de rochas ornamentais: Uma análise para aplicação na perfuração de rochas carbonáticas(Universidade Federal do Espírito Santo, 2025-08-28) Moreira, Kelly Costa Cabral Salazar Ramos; Dalmaschio, Cleocir José ; https://orcid.org/0000-0002-3773-5786; http://lattes.cnpq.br/5209978120430790; Nascimento, Andreas; https://orcid.org/0000-0002-4465-5450; https://buscatextual.cnpq.brhttp://lattes.cnpq.br/2072155247986639; https://orcid.org/0000-0003-4651-6785; http://lattes.cnpq.br/4803056863749096; Mantegazini, Diunay Zuliani ; https://orcid.org/0000-0003-0606-5991; http://lattes.cnpq.br/1059490151468461; Siqueira, Renato do Nascimento ; https://orcid.org/0000-0002-8397-8180; http://lattes.cnpq.br/9791817633014124; Soares, Edson José ; https://orcid.org/0000-0003-4967-4957; http://lattes.cnpq.br/4485206584533650; Machado, Marta Albuquerque ; https://orcid.org/0000-0001-8335-3351; http://lattes.cnpq.br/5991893415892784Xanthan gum (GX), widely used in drilling fluids, undergoes polymer chain degradation and changes in its properties at high temperatures. Minerals such as bentonite are also common additives used to adjust fluid properties. However, their limitations in carbonate formations have driven the search for alternative mineral additives. Ornamental Rock Waste (RRO), a byproduct of granite and marble processing, is an available mineral whose disposal presents a significant challenge. In this context, this study proposes the use of RRO as a partial or total substitute for bentonite in aqueous fluids with GX, evaluating its influence on the polymer’s thermal stability. Two types of waste (RRO FD and FH) were characterized, with RRO FD selected for the formulations. The characterization of GX confirmed its structure, and thermogravimetric analysis revealed mass losses at 79 °C and 277 °C, associated with adsorbed water and volatiles, respectively. Kinetic evaluation (30–55% conversion) indicated an average activation energy of 177 kJ·mol⁻¹, typical of biopolymers. The z Master plot analysis suggested that degradation begins with rapid nucleation in the side chains, exposing the main chain to progressive thermal fragmentation. The pseudoplastic behavior of GX solutions was confirmed, and aging tests showed greater polymer degradation at temperatures above 140 °C (static) and above 100 °C (dynamic, 600 rpm). Thus, in dynamic aging, degradation was more severe due to the early loss of side chains. The addition of RRO to the polymeric fluid reduced viscosity, yield stress, and thixotropy, and also resulted in unstable suspensions. To improve this interaction, RRO was treated with terephthalic acid (TPA), stabilizing the particles in an alkaline medium. The reaction with ethylenediamine (EDA) and GX produced the RTPEX composite, confirmed by FTIR through the formation of amide bonds (C=O at 1653 cm⁻¹ and N-H at 1546 cm⁻¹). Fluids containing RTPEX showed improved rheological performance, especially at low shear rates. As the shear rate increased, the composite structure was broken, reducing its rheological properties. Flow curves adjusted using the Herschel-Bulkley and Power-Law models revealed shear-thinning behavior. The fluid with 100% bentonite (B 100%) exhibited the highest viscosity and yield stress (2.7412 Pa) due to its interaction with GX. The fluid combining RTPEX and bentonite at a 50:50% ratio (m/m) (RTPEX_B) showed comparable rheological performance to B 100%, indicating the formation of a stable three-dimensional network. Adjusting the pH to 10 improved the rheological parameters of the fluids containing RTPEX and bentonite, including the 100% RTPEX fluid, due to deprotonation of acidic groups. In thixotropy tests, RTPEX_B showed the largest hysteresis loop area (1431.6 Pa·s⁻¹), surpassing B 100% (1347.39 Pa·s⁻¹), reinforcing the synergy between components. After dynamic thermal aging, RTPEX_B maintained superior parameters, indicating greater resistance to degradation under shear. The results demonstrate the potential of RTPEX as a partial substitute for bentonite. To assess the economic viability of this reuse, a case study was conducted at an ornamental stone company in Espírito Santo, indicating the potential for significant reductions in operational costs for the ornamental stone industry
- ItemCompostos de coordenação de cobalto com ligantes redox ativos do tipo o-aminofenóis(Universidade Federal do Espírito Santo, 2024-12-19) Bruzeguini, Carlos Eduardo Tartaglia; Ribeiro, Marcos Antônio ; https://orcid.org/0000-0002-9350-6419; http://lattes.cnpq.br/3587612609487639; https://orcid.org/0000-0003-1645-0535; http://lattes.cnpq.br/8086360034550152; Pinheiro, Carlos Basílio ; https://orcid.org/0000-0002-8674-1779; http://lattes.cnpq.br/9481262314079347; Rocha, Julio Cesar da ; https://orcid.org/0000-0003-3705-3344; http://lattes.cnpq.br/8594471074402807; Cunha Neto, Alvaro ; https://orcid.org/0000-0002-1814-6214; http://lattes.cnpq.br/7448379486432052; Dalmaschio, Cleocir José ; https://orcid.org/0000-0002-3773-5786; http://lattes.cnpq.br/5209978120430790Redox-active ligands are a class of organic ligands that exhibit reduction and oxidation processes, presenting species with different charges and ambiguity in the oxidation state. When coordinated to metal centers, these ligands maintain these processes independent of the metal ion. The coordination compounds formed with this class of ligands exhibit electronic properties that cause them to exhibit redox and magnetic properties. Due to these characteristics, redox-active ligands are explored in catalysis applications and in the study of radical systems. They are important constituents for the formation of systems that exhibit valence tautomerism (VT) characteristics. This will exhibit electronic lability, that is, they have two quasi-degenerate electronic states, with close and accessible energy values. These states are interconverted with the help of external disturbances, such as temperature variation, incidence of light and pressure. The change between these states results in different optical and/or magnetic properties for the compound. This behavior is characteristic of the application of functional materials in molecular electronic devices, as it can specify a function for each property. The aim of this research was to evaluate whether o-aminophenol ligands can replace dioxolene ligands, which are the most used redox-active ligands in VT systems, to observe new compounds with the valence tautomerism phenomenon. For this purpose, the ligands H4L and H4dP, both o-aminophenols, were selected to form progression compounds with cobalt and iron metal centers. The products obtained had their structures determined by X-ray diffraction. From the analysis of the structures of the obtained compounds, it was concluded that the systems produced did not exhibit VT. In addition, the characteristics of the chosen ligands, conformational freedom and high reactivity, showed that they tend to form radical species in solution, promoting parallel reactions of intramolecular cycles and homolytic bond breaks. By studying the structures obtained, it is assessed that to form systems with VT using redox-active ligands of the aminophenol type, they must be those that preferentially coordinate in the iminosequinone species. For this, the ligand must have a tertiary amine or be an imine, unlike H4L and H4dP, which coordinated as aminophenolate