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This study aimed to study the interaction between two different açaí extracts used in synthesis of hybrid polymeric films based on chitosan–clay and evaluate its morphological and physical–chemical properties, indeed antibacterial and antioxidant activities. Films with acidified açai extract (FEAA) and non-acidified açai extract (FEBANA) were prepared using the casting method. It was possible to observe a surface with a rough appearance, varying according to the added extract concentration using SEM photomicrographs. The reflection peaks were similar to the Chit–Clay film (2θ = 14° and 16.8°) and the reduction in the degree of chitosan crystallinity for the FEBANA films in relation to FEAA films. The TG data also show that the FEBANA films have a higher percentage of water of hydration than the FEAA films, corroborating this state of anhydrous films for FEAA and state of hydrated films for FEBANA. The FEBANA films were two stretches in the region between 842 and 962 cm−1, and a shoulder 1095 cm−1 covered by bands 1025 cm−1 (Si–O–Si) and can attributed to the PEG plasticizer. This greater detection of PEG stretches in the FEBANA films suggests a greater concentration of PEG on the surface of the FEBANA film. MIC microbiology demonstrated that both types of extracts were capable of inhibiting Gram (−) strains, Escherichia coli and Pseudomonas aeruginosa, and Gram (+) strains, Staphylococcus aureus and Staphylococcus epidermidis. In disk diffusion, the acidified extract showed inhibition activity for Edwardsiella tarda, Enterococcus faecium and Streptococcus pyogenes. Both extracts are effective in inhibiting the growth of both Gram (−) and Gram (+) bacteria. The FEAA polymeric films showed a higher degree of recovery, reversible chemical bonding with the matrices and consequently greater DPPH free radical scavenging capacity compared to the FEBANA polymeric films. The FEAA and FEBANA films present characteristics of releasing active ingredients from the hybrid polymeric film and can be applied in edible packaging or use in biodegradable smart packaging or as food biopreservative; or even, in pharmaceutical release systems for releasing active ingredients onto the skin, as organic active ingredient release membranes for skin health and beauty, wound healing or even as adjuvants in tissue bioengineering for skin reconstruction after burns and in plastic skin surgery as biodegradable films. [ABSTRACT FROM AUTHOR]

This work focuses on the obtaining and the bactericidal properties study, in vitro, of hybrid films as potential coating materials to inhibit bacteria proliferation. In consequence, hybrid films from nickel oxide (NiO) and nickel ferrite (NiFe2O4) nanoparticles (NPs) embedded in poly-3-hydroxybutyrate (P3HB) were obtained by the solvent casting method. P3HB@NiO and P3HB@NiFe2O4 hybrid films and P3HB film were characterized by X-ray diffraction (XRD), Raman scattering, and scanning electron microscopy (SEM). The XRD of the hybrid films showed that NiO and NiFe2O4 NPs incorporated in the P3HB conserved their nanometric size, and by Energy-dispersive X-ray spectroscopy (EDS) were observed that NPs are homogeneously distributed in the films. The bactericidal effect of the obtained films was evaluated in vitro from the broth surface method against two opportunistic and nosocomial pathogens, Staphylococcus aureus and Pseudomonas aeruginosa. The results showed that P3HB film, P3HB@NiO, and P3HB@NiFe2O4 hybrid films reduced 90%, 98%, and 97% of the growth of S. aureus, respectively. For P. aeruginosa, their growth was reduced by 90%, 94%, and 96%, respectively. In addition, the cytotoxic effect of NiO and NiFe2O4 NPs, as well as P3HB film, and P3HB@NiO, and P3HB@NiFe2O4 hybrid films was evaluated using human skin cells; keratinocytes and fibroblast, being the NPs less cytotoxic than films. Although P3HB is known as a biocompatible polymer, here is demonstrated that in our work conditions, their films have bactericidal properties and are cytotoxic to keratinocytes and fibroblasts, the first barrier of the human skin. However, the P3HB@NiO and P3HB@NiFe2O4 hybrid films synergize the bactericidal effect between the P3HB and the NPs. On the other hand, the NPs decrease the P3HB cytotoxicity to keratinocytes. The methodology used in this work is particularly suitable for producing hybrid films with antibacterial activity against Gram-positive and Gram-negative bacterial strains. [ABSTRACT FROM AUTHOR]

Hybridization of layered 2D molybdenum disulfide (MoS2) films via intercalation of guest molecules and ions has recently emerged as a powerful tool to enhance its catalytic activity and stability of electrochemical hydrogen evolution reaction. In this study, we report that intercalation of histidine amino acid fragments, formed via the thermal decomposition of amino acid to the low molecular weight planar peptide species –Cα–CO–N–Cα–, in an inter sheet space of nanostructured MoS2 during the hydrothermal synthesis results in the surprisingly high hydrogen evolution reaction catalytic activity and stability. We ascribed this effect to the preferred formation and protection of 1T-MoS2 phase from the transformation to more stable 2H-MoS2 phase during hydrogen evolution reaction processing triggered by the inserted peptides species. Scanning electron microscopy, high-resolution transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry methods were applied for characterization of the synthesized products exposing histidine impact. [ABSTRACT FROM AUTHOR]

This research aimed to develop films based on chitosan/polyvinyl alcohol. These films were plasticized with glycerol, sunflower oil, and glucose. Mixtures of chitosan and polyvinyl alcohol were prepared at a ratio of 1:1 (w:w). Plasticizers were added at final concentrations of 20, 40, and 60% (chitosan weight/w). Physicochemical and mechanical properties of films were analyzed. The results indicated that moisture content, degree of swelling and solubility in the films increased due to glucose and glycerol hydrophilic components. However, this effect was not observed when the sunflower oil was used as plasticizer, due to the hydrophobic nature of this compound. The thickness increased as glycerol content raised, but it decreased when the sunflower oil was added. The films tensile stress and elasticity increased with the addition of glycerol but showed opposite results when the sunflower oil and glucose were added. Water vapor permeability increased proportionally with the glycerol concentration. Finally, the films biodegradability decreased when the plasticizers' concentration increased. Functional groups, morphology and thermal degradation were assessed by FTIR, SEM and TGA, respectively. Morphological characterization of the laminated films with glycerol and glucose showed homogeneous surface and small aggregates. Films-plasticizer with Sunflower oil presented low-uniform surface. The results obtained from this research subjects that biodegradable films are suitable candidates to be used for food coating. [ABSTRACT FROM AUTHOR]

This paper describes the fabrication of heteromorphic microlens arrays in the polymethyl methacrylate/titanium/organically modified siloxanes photosensitive hybrid films by UV nanoimprint technique and the applications of the prepared microlens arrays on the organic light-emitting diode. The hybrid films were obtained by combining a sol–gel technique and spin coating method. UV–visible spectroscopy and atomic force microscope are used to characterize the properties of the hybrid films, and the results indicate that the hybrid films have high transmittance and small surface roughness. Scanning electron microscope and surface profile results show that the heteromorphic microlens arrays formed in the hybrid films are uniform and well defined. Optical microscopy results show that the hexagonal microlens arrays have the relatively strong focusing ability and excellent imaging performance. Finally, the microlens arrays are applied to the organic light-emitting diode, the luminous properties of the organic light-emitting diode is enhanced, and there is a maximum improvement of about 43.9% in current efficiency for OLEDs with hexagonal microlens arrays. All the results above indicate that it is a simple and low-cost process to fabricate hybrid film microlens arrays by UV nanoimprint technique, and the prepared microlens arrays have potential applications in the organic light-emitting diode. [ABSTRACT FROM AUTHOR]

The electron accelerator radiation was used for the in situ synthesis of gold nanoparticles (Au NPs) in poly (vinyl alcohol) (PVA) films. The hybrid films were characterized using photoluminescence spectroscopy (PL), differential scanning calorimetry (DSC) and AC electrical conductivity. PL results show an enhancement of the emission spectra of PVA upon the formation of Au NPs in the PVA matrix. The results reveal that irradiation at 200 kGy resulted in the highest intensity of the emission peaks of both PVA and Au NPs. The DSC results indicated that incorporation of metal nanoparticles in the PVA matrix reduces the thinking of the crystalline structure of PVA. AC electrical conductivity, σac for non-irradiated and irradiated samples (100, 200 and 300 kGy) is measured over a temperature range from 303 up to 363 K at an applied field frequency of 5 MHz. The σac values show an increase with temperature and show its highest values at 100 kGy irradiation dose over that temperature range. Dielectric constant (ε1) exhibits an increase with temperature and maximum values at 100 kGy dose, whereas the dielectric loss tangent (tanδ) follows an opposite trend at that dose. [ABSTRACT FROM AUTHOR]

The design and fabrication of multifunctional UV-shielding materials based on naturally abundant and biodegradable raw materials have far-reaching significance for various practical applications and sustainable development. In the present work, novel multifunctional cellulose nanofibrils (CNFs)/halloysite nanotubes-zinc oxide (HNTs-ZnO) hybrid films with synergic feature of excellent UV-shielding, superhydrophobic properties and thermal stability were firstly fabricated via vacuum-assisted filtration strategy and following hydrophobic modification. The successful immobilization of ZnO nano-protrusions on HNTs surface effectively suppressed the aggregation of ZnO nanoparticles, giving a positive contribution for the UV-shielding performance. Particularly, the CNFs/HNTs-ZnO hybrid films achieved a high UV-blocking efficiency in both UVA (95.7%), UVB (98.7%) and UVC (99.8%). Besides, the filtration membrane template endowed the CNFs/HNTs-ZnO hybrid films with hierarchical rough architecture, and as-fabricated hybrid films presented superhydrophobicity with a contact angle over 155° and simultaneous self-cleaning function. Moreover, the CNFs/HNTs-ZnO hybrid films also displayed an outstanding thermal and UV stability. The findings conceivably indicate that the CNFs/HNTs-ZnO hybrid films provide a versatile way for the development of sustainable multifunctional UV-shielding films and have promising applications in packaging, intelligent windows and other outdoor UV-sensitive materials areas. [ABSTRACT FROM AUTHOR]

Electronic and fluorescence spectroscopy was used to show that the aggregation of rhodamine 6G molecules in a film-forming sol and derived hybrid films is a function of the equilibrium dye concentration and the micelle-forming agent and, as a consequence, the concentration of the micelle-forming agent in the film-forming sol affects the optical characteristics of the hybrid sol-gel films. Dye monomers were found to predominate in the sol, while the formation of nonplanar luminescent H-dimers is possible during film formation as a consequence of geometrical limitations of the dye molecules solubilized within the micelles. [ABSTRACT FROM AUTHOR]

The organic material soluble polyimide (PI) and organic-inorganic hybrid PI-barium titanate (BaTiO) nanoparticle dielectric materials (IBX, where X is the concentration of BaTiO nanoparticles in a PI matrix) were successfully synthesized through a sol-gel process. The effects of various BaTiO contents on the hybrid film performance and performance optimization were investigated. Furthermore, pentacene-based organic thin film transistors (OTFTs) with PI-BaTiO/polymethylmethacrylate or cyclic olefin copolymer (COC)-modified gate dielectrics were fabricated and examined. The hybrid materials showed effective dispersion of BaTiO nanoparticles in the PI matrix and favorable thermal properties. X-ray diffraction patterns revealed that the BaTiO nanoparticles had a perovskite structure. The hybrid films exhibited high formability and planarity. The IBX hybrid dielectric films exhibited tunable insulating properties such as the dielectric constant value and capacitance in ranges of 4.0-8.6 and 9.2-17.5 nF cm, respectively. Adding the modified layer caused the decrease of dielectric constant values and capacitances. The modified dielectric layer without cross-linking displayed a hydrophobic surface. The electrical characteristics of the pentacene-based OTFTs were enhanced after the surface modification. The optimal condition for the dielectric layer was 10 wt% hybrid film with the COC-modified layer; moreover, the device exhibited a threshold voltage of 0.12 V, field-effect mobility of 4.32 × 10 cm V s, and on/off current of 8.4 × 10. [ABSTRACT FROM AUTHOR]

We report the thermoelectric (TE) properties of organic-inorganic hybrid thin films composed of conductive polymer, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS), and inorganic silver nanowire (AgNW). Two kinds of AgNW with different wire length, 3 μm and 27 μm, were used in this study. The AgNW/PEDOT-PSS hybrid films showed an increase in electrical conductivity ( σ) with increase in AgNW concentration. The maximum value of σ obtained in this system was ca. 10,000 S cm. The films containing long AgNWs (L-AgNWs) showed higher σ relative to short AgNWs (S-AgNWs) at given concentration, which results from the fact that longer nanowires can easily form a percolated structure. The formation of a percolated structure was confirmed by scanning electron microscopy (SEM) observation. On the other hand, the Seebeck coefficient ( S) of the hybrid films showed the opposite dependence on AgNW concentration. This decrease in S with increasing AgNW concentration is probably because of increase in carrier number due to the AgNWs. These results suggest that the presented organic-inorganic hybrid system is one example where the electrical conductivity and TE properties can be tuned by use of a nanocomposite. [ABSTRACT FROM AUTHOR]

SrSiN:Eu-cellulose hybrid films were successfully prepared, by use of a green sol-gel transition method, from cellulose and a sunlight-conversion agent. Cellulose quickly dissolved in 7 wt% NaOH-12 wt% urea aqueous solution at low temperature, as a result of a fast dynamic self-assembly process. The SrSiN:Eu particles were embedded firmly in the cellulose matrix, as a consequence of a strong interaction between the cellulose and the particles. Results from scanning electron microscopy, absorption spectroscopy, fluorescence spectroscopy, and tensile testing confirmed the hybrid films had a homogenous structure, wide absorption, strong fluorescence emission, and good tensile properties. Moreover, fluorescence spectroscopy confirmed that the excitation and the emission intensity of films were related to the concentration of the SrSiN:Eu. The mechanical properties could be improved by adjustment of the concentration of SrSiN:Eu. This work has provided a new method for preparation of sunlight-conversion films; the process has potential for large-scale application and is expected to be used in greenhouse planting. [ABSTRACT FROM AUTHOR]

To enhance the thermal stability and barrier properties of pure poly(vinyl alcohol) (PVA), a series of poly(vinyl alcohol)/vinyltrimethoxysilane (PVA/VTMS) hybrid films were prepared via a sol-gel process, and their physical properties were investigated as a function of VTMS content. During the sol-gel process, simultaneous reactions between hydroxyl groups of PVA and silanol groups of hydrolyzed VTMS and self-condensation of VTMS occurred, inducing a cross-linked network structure and greatly enhanced thermal stability and oxygen barrier properties. The glass transition temperature and thermal decomposition temperature ( T) of the PVA/VTMS hybrid films increased from 72.6 to 84.3 °C and 273.6 to 342.2 °C, respectively, with increasing VTMS content from 0 to 20%. Oxygen transmission rates of the hybrid films decreased from 6.12 to 0.17 cm/m×day, and those of the hybrid films incorporating 5%, 10%, and 20% VTMS were suppressed by 65.7%, 95.6%, and 97.2%, respectively, versus a pure PVA film. These are dependent on the chemical structure and morphology of the films with differing initial amounts of VTMS. The chemical affinity for water, intermolecular packing, and rigidity in polymer chains increased with increasing cross-linking by VTMS, leading to enhanced oxygen barrier properties and thermal stability in the PVA/VTMS hybrid films. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Highly ordered TiO-based films and powders organized by template synthesis using the sol-gel method were obtained. New templates of different nature; i.e., polyethyloxazoline, polyethylene glycol monooleate, polyethylenimine, and traditional dodecylamine, were used as modifying additives. The effect of the activity of functional amino groups containing primary, secondary, and tertiary amines on the physico-chemical properties of films and powders was studied. The effect of such materials on the powder composition was examined by X-ray phase and structural analysis, low-temperature nitrogen adsorption-desorption, and film morphology using atomic force microscopy and small-angle X-ray scattering. The mechanism of the chemical reaction according to the IR spectral data is described. The change in modifier activity significantly affects the composition and properties of the end product and may lead to a high degree of self-organization of the formed surface not only at the nano level but also at the micro level. The comparative description of the photoactivity of the films and powders and modifier origin is given. [ABSTRACT FROM AUTHOR]

The conductive nano-sized zinc particles were embedded in an insulating amorphous silica matrix, and the hybrid films were obtained by a sol-gel method. The stable hybrid sol solution was prepared by hydrolysis and condensation of Methyltrimethoxysilane (MTMS) with a one-step acidic catalyst process. Hybrid films were dip-coated on silicon wafer and cured at 120 °C for 60 minutes. The structural characterization of hybrid films were investigated by means of attenuated total reflection infrared (ATR-IR) spectroscopy and X-ray diffraction (XRD). The electrical properties of the films were examined with four-point probe. Hybrid films showed to be relatively dense, uniform and defect free. The conductivity of hybrid films was varied with the different contents of zinc nanoparticles and the thickness of the film. It was observed that there was the percolation threshold for the film's electrical properties. [ABSTRACT FROM AUTHOR]

Polyimide/silica/silver hybrid films were prepared by the sol-gel method combined with in situ single-stage self-metallization technique. The structure of polyimide films in the thermal curing process and the influence of silica content on the migration and aggregation of silver particles to the surface of hybrid films were investigated. The hybrid films were characterized by transmission electron microscopy, dynamic mechanical thermal analysis, Fourier transform infrared spectroscopy, ultraviolet visible spectroscopy and mechanical measurements. The results indicated that there was no degradation of the polyimide matrix after the formation of silica and silver particles. Silica acted as the nucleus for the silver particles. With increasing silica content, more and more silver particles were kept in the hybrid films instead of being migrated onto the surface of the hybrid films and the reflections of hybrid films decreased gradually. [ABSTRACT FROM AUTHOR]

The preparation and properties of polyglycidol (PGLD)/silica hybrid gels were investigated. The gels were synthesized by the reaction of hyperbranched PGLD and triethoxysilyl-capped poly(ethylene oxide) in the presence of colloidal silica 80 nm in size or tetraethyl orthosilicate (TEOS) under acidic circumstances. The crosslinking reaction gave hybrid gels with a relatively high gel fraction over 98%. The degree of gel swelling obtained by the reaction using colloidal silica and TEOS decreased with SiO2 content, while the stiffness of the gels increased with SiO2 content. Gels prepared from TEOS exhibited a swelling ratio ranging from 25% to 40%, which was relatively higher than those from colloidal silica. They also demonstrated a higher stiffness in comparison to those from colloidal silica, probably due to high crosslinking. [ABSTRACT FROM AUTHOR]

The physical properties of inorganic-organic sol-gel hybrid films are determined by a large number of processing parameters, as the initial recipe, the catalysis conditions and the film deposition technique. This work focuses on the influence of the precursor solution's ageing on the quality and structure of hybrid silica-polytetrahydrofuran films, prepared by spin coating. The inorganic precursor, tetraethylorthosilicate, was hydrolysed under acid catalysis and using ethanol as co-solvent. The hydrolysis molar ratio ( R) was fixed at 4. Different polymer concentrations of two average molecular weights ( Mn = 650 and 2900) were added to the initial colloidal solutions. Ageing took place in open containers. The thickness and surface texture parameters of the films were determined by profilometry, and their structures studied by FTIR. It is shown that the films' thickness increases with the ageing of the precursor solution, more steeply for the hybrid films with higher polymer content and higher Mn. The best films obtained, which present the highest thickness and the lowest relative roughness, are those prepared from the most aged solutions. The FTIR results show that the films' porosity increases with the ageing of the precursor solution, and that the distribution of oligomeric species in solution is maintained upon film deposition. Therefore, the structure of the film is essentially determined by the extension of the condensation reactions until the spinning moment. [ABSTRACT FROM AUTHOR]

The influence of the solvent on the thickness, morphology and structure of silica-polytetrahydrofuran hybrid films, prepared by spin coating, has been analysed. The inorganic precursor, tetraethylorthosilicate, was hydrolysed under acid catalysis, the hydrolysis molar ratio being 4. Polymers of average molecular weight ( Mn) 650 and 2900 were incorporated in the initial colloidal solutions, in a low concentration (organic/inorganic molar ratio 0.01). Two solvents were compared: ethanol, protic, and tetrahydrofuran, aprotic and a little less polar. The thickness and surface texture parameters of the films were determined by profilometry, their morphology characterized by SEM and their structure studied by FTIR. It is shown that the solvent has no effect on the molecular structure of the films, but strongly influences the surface texture and the morphology of both pure silica and hybrid films. The solutions prepared in tetrahydrofuran present shorter gelation times ( tG) and allow the deposition of good quality films almost up to the gelation point (to a reduced time, t/tG, of ∼0.9). The films are thinner than those prepared from corresponding ethanolic solutions at the same reduced ageing times. For pure silica films, tetrahydrofuran is the best choice, since it reduces the fractured region on the edge of the substrate. For hybrid films, this effect is achieved by the polymer and tetrahydrofuran is responsible for a higher arithmetical mean roughness. Therefore, ethanol becomes the preferable solvent. [ABSTRACT FROM AUTHOR]

The sol-gel process has been used to prepare hybrid silica gel-polytetrahydrofuran (PTHF) thin films, using tetraethylorthosilicate (TEOS) as the precursor. The films were prepared by spin-coating, and characterized by profilometry, transmission FTIR and SEM. Film properties were conditioned by the preparation procedure as well as by the initial recipe, namely the solvent, polymer content and molecular weight. Evidence was obtained of the participation of the polymer in the condensation step of the process, interacting by hydrogen bonds with hydroxyl groups of the silicate network. [ABSTRACT FROM AUTHOR]