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Polyethylene terephthalate (PET) waste has become a major challenge for the conservation of the environment due to difficult degradation. For this reason, it is important to develop new recycling strategies for reusing this waste. In this work, the electrospinning technique was used to synthesize composite nanofibers of polyvinylpyrrolidone (PVP), recycling PET (RPET) that was obtained from the chemical recycling of postconsumer PET with glycolysis and styrene (ST) as a crosslinking agent. The polymer solutions were analyzed by viscosity and frequency sweeping, while the composite nanofibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and nanoindentation to compare their properties. The PVP nanofibers presented an average diameter of 257 nm; the RPET/PVP and RPET/PVP/ST composite nanofibers had average diameters of 361 nm and 394 nm, respectively; and the modulus of elasticity and hardness of the RPET/PVP/ST composite nanofibers were 29 and 20 times larger, respectively, than those of the PVP nanofibers. With the synthesis of these composite nanofibers, a new approach to PET recycling is presented.

Recently, green chemistry for the development of sustainable production systems requires tremendous research efforts on the design of catalysts through resource-efficient ways. The improvement of their catalytic performances is a key goal in modern society. Several approaches using environmentally friendly chemicals and materials for less hazardous synthesis and catalysis were analyzed. In this review, we focus on the synthesis of nanomaterials and catalytic applications to reduce the environmental impact, especially, by reducing waste, solvents, precursors, and derivatives. In addition, we highlight the special efforts toward the use of renewable feedstocks and their applications as well as the synthetic routes to develop nanocatalysts using a greener chemistry.

In this study, the effect of the addition of polyacrylonitrile microfibers (PAN) on the mechanical properties, durability and drying shrinkage of mortar was investigated. PAN microfibers synthesized by the electrospinning technique were used; the average diameter and length of the microfibers was 1.01 µm and 10–25 µm, respectively. The results of the experimental study indicate that the addition of PAN microfibers enhanced the mechanical properties and some parameters related to durability, and drying shrinkage was considerably reduced. Therefore, reinforcing mortar with PAN microfibers is a viable option to improve the performance of this material and expand its application.

We report the low-temperature (100 °C) processing and characteristics of PS TiO2 cross-linked hybrid films, obtained by a simple sol-gel route using titanium butoxide (TB) as the inorganic source, styrene (ST) as the organic source, and 3-trimetoxy-silyl-propyl- methacrylate (TMSPM) as the coupling agent. The films were characterized by FTIR to identify the characteristic chemical groups. TGA determined the content of the organic and inorganic components. AFM and SEM images revealed the homogeneous and smooth surface with very low roughness of the hybrid films. At macroscopic level, the hybrid films were homogeneous with high transparency and high refractive index, determined from optical spectroscopy. These characteristics support the formation of a cross-linked hybrid material with strong bonds between organic and inorganic phases. The hybrid films dielectric characteristics were studied by measuring capacitance-voltage (C V) and current-voltage (I V) curves in metal-insulator-metal (MIM) structures. The dielectric constant measured was 5.2 and leakage current around 10−6 A/cm2.

TiO2-RGO (TG) nanocomposite applied as photocatalysts have been synthesized via a facile low-temperature wet chemistry process, during which the reduction of graphene oxide (RGO) and the growth of titanium dioxide (TiO2) nanoparticles on the RGO nanosheets are achieved simultaneously. RGO role in TG nanocomposites as photocatalysts were analyzed in methylene blue photocatalytic degradation under UV and solar irradiation. The TG nanocomposites were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The photocatalytic efficiency of the TG-30 sample under UV and TG-45 solar irradiation was ∼7 and ∼5 times that of pristine TiO2, respectively. The enhancement of the photocatalytic activity with UV irradiation in TG was attributed to the high separation efficiency of photoinduced electron–hole pairs, while the enhancement of photocatalytic activity with solar irradiation in the TG was attributed to RGO role, acted as a photosensitizer and a charges separator, simultaneously.

A highly sustainable method for the preparation of supported iron oxide and copper nanoparticles (NPs) on a biomass-derived carbon by solvent-free mechanochemical process is reported. In-situ mechanochemically obtained extracts from orange peel could behave as a green reducing agent, allowing the formation of Cu metal nanoparticles as well as generating a magnetic phase (magnetite) in the systems via partial Fe3+ reduction. At the same time, orange peel residues also served as template and carbon source, adding oxygen functionalities, which were found to benefit the catalytic performance of mechanochemically synthesized nanomaterials. The series of magnetic Cu-Fe@OP were tested in the oxidation of trans-ferulic acid towards vanillin, remarkably revealing a maximum vanillin yield of 82% for the sample treated at 200 °C.

Consumption of polyethylene terephthalate (PET) products has increased dramatically in recent decades, resulting in the generation of a large amount of PET waste. For that reason, is necessary to find a new application of recycled material. In this article, we report the synthesis and characterization of recycled poly (ethylene terephthalate) (RPET) obtained from the chemical recycling of post-consumer PET bottles by glycolysis method and the formation of composites nanofibers RPET/polyacrylonitrile (PAN)/styrene (ST). The RPET synthesis was studied through infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The viscosity and frequency sweep of the polymeric solutions was evaluated. The composites nanofibers were elaborated by the electrospinning technique and characterized by scanning electron microscopy (SEM), FT-IR, TGA/DSC and nanoindentation. The RPET/PAN/ST composite nanofibers present an average diameter of 456 nm and higher thermal stability compared PAN fibers. The mechanical properties such as hardness and elastic modulus were 4.5 and 7.5 times PAN fibers values, respectively.

In this work binary Sn-Ti samples having Sn:Ti atomic ratios from zero to one were prepared through a hydrothermal method. The resulting high surface area powders were characterized using a combination of X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, UV–vis spectroscopy and porosimetry techniques. The series of samples covers catalysts with anatase and rutile type structures. Each sample is composed of a main (anatase or rutile) Ti1-xSnxOy phase decorated by different Sn-containing entities. The photo-catalytic performance in the 2-propanol photo-oxidation was assessed through the measurement of the reaction rate and true quantum efficiency. The latter required the measurement of the optical properties of the powders and the computation of the local superficial rate of photon absorption. Although relatively similar activity maximum can be obtained for anatase and rutite type samples based in the comparison of the reaction rates, the calculation of the true quantum efficiency demonstrates that the optimum anatase type material displays superior performance than the rutile one. The physico-chemical origin of this behavior is analyzed in terms of the electronic and structural properties of the binary Sn-Ti samples.

This work focuses on the studies of titanium butoxide (Ti(OBu)4) molar ratio effect in the TiO2 nanoparticles size via solvothermal method for methylene blue degradation. The materials used for the synthesis were: Ti(OBu)4 as titanium source, anhydrous ethanol (EtOH) as solvent, and nitric acid (HNO3) as catalyst. The TiO2 nanoparticles demonstrate growth in a pure anatase phase tetragonal crystalline structure, where other phases or amorphous material is not present. The TiO2 nanoparticles reveal a rounded shaped and when the amount of titanium precursor increases, the nanoparticle size decreases. The photocatalytic degradation of methylene blue is influenced by the nanoparticle size where the material with a 2:30:2 molar ratio, Ti(OBu)4:EtOH:HNO3, presents the minor nanoparticle size and a degradation similar to results obtained by commercial TiO2 (P25) at a time of 90 min.

We report a simple sol–gel process for the deposition of poly(methyl methacrylate) (PMMA)–ZrO2 organic–inorganic hybrid films at low temperature and studied their properties as a function of the molar ratios of the precursors in the hybrid sol–gel solution, which included zirconium propoxide as the inorganic (zirconia) source, methyl methacrylate as the organic source, and 3-trimethoxy-silyl-propyl-methacrylate (TMSPM) as the coupling agent to enhance the compatibility between the organic and inorganic phases. The hybrid thin-film deposition was done on glass slide substrates by the dip-coating method. After deposition, the films were heat-treated at 100 °C for 24 h. The analysis of the hybrid films included Fourier transform infrared spectroscopy to identify their chemical groups and thermogravimetric analysis to determine the content of their organic and inorganic components. In addition, capacitance–voltage (C–V) and current–voltage (I–V) curves in metal–insulator–metal structures, using gold as metal ...

We report a novel high-k hybrid material synthesized at low temperature using a simple sol-gel derived method compatible with organic large-area application. The homogeneous cross-linked organic-inorganic dielectric film is achieved by solution process and densified at 100 °C. For the synthesis, styrene and zirconium isopropoxide are used as polystyrene and ZrO2 source, respectively. Also, the 3-trimetoxy-silyl-propyl-methacrylate was used as a coupling agent to link organic and inorganic phases. The hybrid films were deposited by dip coating and densified in-situ by polymerization and polycondensation of the organic and inorganic components. The hybrid materials were analyzed by FTIR, XPS, and TGA measurements to confirm the formation of the cross-linked hybrid material. Optical T and R spectroscopy, AFM, and SEM images demonstrated their optical properties, smooth surface, thickness, and high-quality films. The dielectric constant of 9.2 and leakage current around 10−7 A/cm2 was determined by analyzing the MIM capacitors electrical response, fabricated with the hybrid films as the insulator layer.

We demonstrate low-temperature processed and high-gain unipolar inverters operating at voltages as low as $V_{D} = 1$ V. A maximum gain for a two-transistor unipolar inverter of 153 was achieved at $V_{D} = 5$ V with the advantage of using a solution-based n-type semiconductor and an entire fabrication process below 150 °C. We evaluate the impact of the gate dielectric thickness on the main thin-film transistor (TFT) parameters and operation voltage. In addition, we compare the conventional MOSFET square-law model indistinctly used in TFTs with a model specifically developed for TFTs. We demonstrate a methodology to model the TFT electrical characteristics and use the extracted parameters in SPICE simulations to evaluate different inverter configurations. Finally, we validate the SPICE simulations with our experiential results.

In these days, the inappropriate disposal of polyethylene terephthalate (PET) causes severe environmental problems and, for this reason, it is necessary to develop alternatives for the efficient use of this material. This study presents an application of a new type of composite nanofibers made with recycled PET and polyacrylonitrile (RPET/PAN) recently synthesized and characterized by Scanning Electron Microscopy (SEM), Fourier-Transformed Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). The composite was added to cementitious materials to improve the mechanical and durability properties, making it a viable alternative in PET recycling. With this aim, the following properties were evaluated to mortars prepared with small amounts of these nanofibers: mechanical (compressive and flexural resistance), of the microstructure (fiber adherence) and durability (total porosity, effective porosity, capillary absorption, and resistance to water penetration). These nanofibers have an average diameter of 402 nm and good mechanical properties. Among other important results, the material showed an increase in compressive and flexural strength, and a decrease in drying shrinkage of up to 26.1, 89.1 and 93.1% in comparison with a reference mortar, respectively.

Bragg mirrors (BM) based on TiOx and SiO2 layers were built on glass and PET substrates at operating wavelength in the visible region. The layers were processed by the sol–gel method at room temperature and dried in air for one hour at 100 °C (glass) and 70 °C (PET). At these deposition conditions, the refractive indices of the TiOx and SiO2 layers were 2 and 1.49, respectively. The BM were assembled in a multilayer stack of quarter-wave thickness of alternately high and low refractive index materials. We report the experimental and simulated optical reflection spectra of TiOx–SiO2 BM for different number of layers pairs.

The structural, optical and dielectric characteristics of PMMA–TMSPM–SiO2 hybrid thin films, synthesized by sol–gel, were studied as a function of the molar concentration of the coupling agent (TMSPM) in the hybrid precursor solution. It was possible to obtain very homogenous films, with improved thermal stability and variable organic and inorganic composition. The hybrid films showed high uniformity, excellent optical transparency and tunable refractive index from 1.447 to 1.490 at 633 nm depending on the PMMA fraction in the films. The formation of both organic and inorganic components and their interaction in the hybrid material were confirmed by the analysis of the ATR–FTIR spectra, suggesting changes in the film structure caused by the variations of the TMSPM concentration. The dielectric constant of the hybrid films, determined from capacitance–voltage (C–V) measurements performed in metal–insulator–metal (MIM) configuration, had unexpectedly high values between 5 and 14, increasing with decreasing TMSPM molar ratio. Such high dielectric constant values were attributed to highly polarizable OH and C C groups in the hybrid films, OH being part of the residual precursor solvents and C C the result of incomplete conversion of precursor monomer (MMA) into polymer (PMMA), as shown by FTIR measurements. Furthermore, the dielectric constant of the hybrid films was modeled according to an effective media approximation model, taking into account the constituting organic and inorganic phases, residual O H and C C groups.

In this work we report the synthesis process and properties of PMMA-ZrO2 organic–inorganic hybrid films. The hybrid films were deposited by a modified sol-gel process using zirconium propoxide (ZP) as the inorganic (zirconia) source, methyl methacrylate (MMA) as the organic source, and 3-trimetoxy-silyl-propyl-methacrylate (TMSPM) as the coupling agent between organic and inorganic phases. The films were deposited by dip coating on glass slide substrates from a hybrid precursor solution containing the three precursors with molar ratio 1 : 0.25 : 0.25 for ZP, TMSPM, and MMA, respectively. After deposition, the hybrid thin films were heat-treated at 100°C for 24 h. The macroscopic characteristics of the hybrid films such as high homogeneity and high optical transparence evidenced the formation of a cross-linked, interpenetrated organic–inorganic network. The deposited PMMA-ZrO2 hybrid films were homogeneous, highly transparent and very well adhered to substrates. Fourier Transform Infra-Red measurements of the hybrid films display absorption bands of chemical groups associated with both PMMA and ZrO2 phases. The amounts of organic and inorganic phases in the hybrid films were determined from thermogravimetric measurements. The surface morphology and homogeneity of the hybrid films at microscopic level were analyzed by scanning electron microscopy and atomic force microscopy images. From the analysis of optical transmission and reflection spectra, the optical constants (refraction index and extinction coefficient) of the hybrid films were determined, employing a physical model to simulate the hybrid optical layers. The refraction index of the hybrid films at 532 nm was 1.56. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42738.