Siloxane-poly(methyl methacrylate) (PMMA) hybrid was synthesized based on the sol-gel method and applied to Ti-6Al-4V through dip-coating. The structural feature of the hybrid was subjected to Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TG); its morphological properties were analyzed through scanning electron microscope (SEM), energy dispersive spectrometry (EDS), atomic force microscopy (AFM) and contact angle. The electrochemical behavior and corrosion resistance of both the hybrid coating and the uncoated substrate were investigated based on electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). Results showed homogeneous coating formation due to the rigid hybrid network formed during polymerization, hydrolysis and condensation reactions. This outcome suggested interaction between the organic (methyl methacrylate (MMA)) and inorganic (tetraethyl orthosilicate (TEOS)) phases, which was favored by the coupling agent (3-(trimethoxysilyl)propyl methacrylate (TMSM)). The S0M (PMMA-SiO2 hybrid Ti-6Al-4V coated alloy) film presented regular topography and adherence to the substrate. Electrochemical simulated body fluid (SBF) tests showed that the hybrid coating presented better barrier properties (168 h of the immersion time) than the uncoated substrate, fact that makes it an interesting material for anti-corrosive applications in biomaterials.

Este trabalho descreve a síntese e caracterização de um novo adsorvente mesoporoso que consiste o MCM-41 funcionalizado com o ácido p-aminobenzóico modificado (PABA-Si). A síntese foi realizada pelo método hidrotermal/co-condensação. O PABA-MCM-41 foi caracterizado usando FTIR, SAXS, adsorção/desorção de N2, MEV e TG. Os experimentos em batelada foram utilizados para determinar os efeitos da concentração inicial do adsorbato, tempo de contato e temperatura. A adsorção do benzo[a]pireno (B[a]P) alcançou o equilíbrio depois de 90 min (q e = 27,2 µg g-1) e concentrações mais altas do adsorbato foram associadas com o aumento, em ambos, da percentagem de remoção (71,0-95,7%) e no valor de q e (20,1-27,1 µg g-1). A adsorção seguiu o modelo cinético de pseudo-segunda ordem, e se ajustou ao modelo de isoterma de Langmuir. Foi verificado em temperaturas mais altas um aumento na taxa inicial de adsorção e na constante cinética. Os parâmetros termodinâmicos indicaram que o processo foi espontâneo, endotérmico e com uma tendência para desordem.

This work describes the synthesis and characterization of a new mesoporous adsorbent consisting of MCM-41 functionalized with modified p-aminobenzoic acid (PABA-Si). The synthesis was performed by a hydrothermal/co-condensation method. The PABA-MCM-41 was characterized using FTIR, SAXS, N2 adsorption/desorption, SEM, and TG. Batch experiments were employed to determine the effects of initial adsorbate concentration, contact time, and temperature. The adsorption of benzo[a]pyrene (B[a]P) reached equilibrium after ca. 90 min (q e = 27.2 µg g-1), and higher adsorbate concentrations were associated with increases in both the percentage removal (71.0-95.7%) and the value of q e (20.1-27.1 µg g-1). The adsorption followed pseudo-second order kinetics, and was fitted using the Langmuir isotherm model. At higher temperatures, there were increases in the initial rate of adsorption and the kinetic constant. The thermodynamic parameters indicated that the process was spontaneous, endothermic, and with a tendency to disorder.