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In this paper, we report the synthesis of different silica materials via the acid-catalyzed sol–gel process at room temperature (25°C), using silane precursors with various alkyl chains (dimethyl, octyl and/or hexadecyl), in order to obtain thin films with anti-reflective and hydrophobic properties. Chemical, optical and structural properties of obtained silica materials were thoroughly characterized with various techniques such as FTIR and UV–Vis spectroscopy, AFM analysis, ellipsometric measurements, ESEM and TEM microscopy. Wettability of thin films was evaluated by water contact angle measurements. FTIR spectra of silica materials revealed that the intensity of the Si–O–Si characteristic bands varies depending on the precursor type. From AFM results, we found that the obtained films present a different microstructure as a function of the silica sol formulations. The hydrophobic character of the thin films increases with increasing the length of the hydrophobic chains following the order: dimethyl

TiO2 – based materials were synthesized via acid-catalyzed sol-gel method using tetraethoxysilane (TEOS) and/or methyltriethoxysilane (MTES) - as silane coupling agents. The physical and chemical properties of the obtained TiO2 – based materials were characterized through FT-IR and UV–Vis spectroscopy, TGA, AFM analysis and contact angle measurements. FT-IR spectra demonstrated that the silane coupling agents react via a cross-link and covalently bond on the TiO2 surface. TGA analysis of samples was used to investigate the effect of addition of silane precursor into the TiO2 matrix. Diffuse reflectance spectra revealed that the addition of silane agents improved the antireflective properties of obtained thin films. Water contact angle of TiO2 - based materials showed that the wettability of the thin films was influenced by the addition of TEOS and/or MTES during the modification process. AFM images showed smooth surfaces (RMS roughness up to 3 nm) but with morphological peculiarities depending on the chemical modification, with TEOS, MTES or both, of the TiO2 parental matrix. Transparent and hydrophobic coatings were obtained with MTES addition in the modification process of TiO2 nanoparticles via acid-catalyzed sol-gel method.

The photochemical degradation of polyolefin-TiO2 composite films was investigated and described in relationship with the concentration of photocatalyst and after different exposure times. UV-Vis-NIR and IR spectra reveal the presence of various degradation products, which are in direct connection with the photodecomposition mechanism. Various ratios between the absorbance of some typical IR characteristic bands can lead to the evaluation of photocomposition of polyethylene and polypropylene composite films containing TiO2 nanoparticles.The results show that the photocatalytic degradation of composites is significantly faster than the simple photolytic decomposition of pure polypropylene and polyethylene and could be used as a solution for the destruction of this type of wastes.

Due to their range of applications, from anti-icing to self-cleaning, low-adhesion, antibacterial. [...]

Currently, hydroxyapatite is probably the most researched material, due to its multiple applications in medical, environmental, or cultural heritage, when the classical structure is modified and calcium is displaced partially or totally with different metals. By changing the classical structure of the hydroxyapatite, new morphologies can be obtained, thus allowing final applications different from those of the initial hydroxyapatite material. However, their properties should be tuned for the desired application. In this context, the present paper describes the synthesis and characterization (through energy-dispersive X-ray fluorescence, X-ray diffraction, FTIR, thermal analysis, and transmission electron microscopy) of iron oxide/manganese-containing phosphatic phase composite materials, developed in order to obtain the enhancement of final environmental applications (photodegradation of dyes, adsorption of organic compounds). The composite material was tested for photocatalytic properties, after embedding in hydrosoluble film-forming materials. Photocatalytic coatings show different activity during the photodecomposition of Methylene Blue, used as a model of a contaminant. The photocatalytic activities of the materials were discussed in relationship with both the phosphatic materials and the magnetic components. Finally, other environmental applications were studied for the developed materials (adsorption of non-steroidal anti-inflammatory drugs&mdash, paracetamol and ibuprofen), revealing an enhancement of the adsorption capacity of the phosphatic material upon addition of the magnetic phase.

Four metal substituted hydroxyapatites (HAPs) were prepared and characterized using energy-dispersive X-ray fluorescence, X-ray diffraction, thermal analysis, and transmission electron microscopy. ...

Seven curcumin derivatives were synthesized by an ecological method, in a microwave field. The compounds obtained were purified and characterized by means of elemental analysis, UV-VIS, fluorescence, IR, 1H-NMR and 13C-NMR spectroscopy. Structure-property relationship in the b-diketone derivatives are discussed with respect to the structure and nature of the substituents for possible applications in optical sensors and luminescent materials.

The seven curcumin derivatives were deposited on palygorskite in order to obtain hybrid materials. The fluorescence emission spectra of the obtained materials show a decrease in fluorescence intensity relative to the respective dyes, due to the environments around the dyestuff molecules created in the host matrices. Absorption studies show the best adsorption on the inorganic matrix, for the compounds with the hydroxyl groups. Correlating fluorescence spectra of hybrid materials with the results for absorption spectra of the dyes adsorbtion on the surface of the clay lead to the conclusion that a high percentage of the adsorbed dye had the effect of fluorescence quenching. Thus, it was confirmed that the fluorescent properties of hybrid materials depend on the interactions established between the fluorescent dyestuff and the inorganic network.

In this study, cellulose nanofibers (CNF) obtained via high-pressure microfluidization were 2,6,6-tetra-methylpiperidine-1-oxyl (TEMPO) oxidized (TOCNF) in order to facilitate the grafting of ethylene glycol methyl ether acrylate (EGA). FTIR and XPS analyses revealed a more efficient grafting of EGA oligomers on the surface of TOCNF as compared to the original CNF. As a result, a consistent covering of the TOCNF fibers with EGA oligomers, an increased hydrophobicity and a reduction in porosity were noticed for TOCNF-EGA. However, the swelling ratio of TOCNF-EGA was similar to that of original CNF grafted with EGA and higher than that of TOCNF, because the higher amount of grafted EGA onto oxidized cellulose and the looser structure reduced the contacts between the fibrils and increased the absorption of water. All these results corroborated with a good cytocompatibility and compression strength recommend TOCNF-EGA for applications in regenerative medicine.

Cellulose is the most abundant renewable biopolymer in nature, being the main constituent of [...]

Several binary composites based on Crystal Violet Lactone (CVL) color former and Phenolphthalein (PPht) developing agent dissolved in 1-tetradecanol (TD) were studied in order to determine how different ratios between components influence the thermochromic behavior of the composites. The color dependence on temperature was investigated in direct relationship with structural changes and interactions between components. The stoichiometry of the colored complex was determined from diffuse reflectance data and confirmed by means of steady state fluorescence measurements and temperature modulated differential scanning calorimetry. The color former: developing agent molar ratio equal to 1:2.5 was determined to ensure the reversibility of the process in optimal conditions. The characteristics of the color path and the influence of thermal history during thermochromic transition were analyzed from the variations of CIELAB color parameters during successive heating/cooling cycles. Dynamic colorimetric properties of the thermochromic binary composite containing the components in optimum ratio are described by four characteristic temperatures in the hysteresis.

The study presents the results regarding the photocatalytic behavior of some water-based styrene-acrylic coatings containing TiO2 nanoparticles sensitized with metal-phthalocyanine tetracarboxylic acids. Coating materials have been studied in terms of color characteristics, photocatalytic behavior, and resistance to self-degradation depending on the structure of phthalocyanine sensitizers. Coatings that were exposed to Xenon light showed degradation of the organic sensitizer rather than of the binder. Photocatalytic tests using methylene blue as a standard contaminant indicated that the coating containing TiO2 nanoparticles sensitized with Fe(III) phthalocyanine tetracarboxylic acids showed the highest efficiency both in ultraviolet or visible light. In this case, the UV light induced a photodegradation rate that was greatly increased of about fifty times comparatively with that induced by LED light and was determined by two different mechanisms, but side reactions like methylene blue and sensitizer self destruction are possible to occur simultaneously. Photocatalytic materials of this type are suitable to be used as decorative coatings especially for indoor applications.