Functional Properties Of Films Research Articles

Impact of functional properties and release kinetics on antioxidant activity of biopolymer active films and coatings

This work deals with the study of the release kinetics of some natural antioxidants (ferulic acid, caffeic acid and tyrosol) from chitosan-fish gelatin edible films immersed ethanol at 96%, as well as the kinetics of their antioxidant activity using the DPPH assay. The aim was to determine how film functional properties influence the release kinetic and antioxidant activity. The addition of antioxidants to chitosan-fish gelatin matrix decreased the water vapour permeability by more than 30%. The tensile strength (TS) increased up to 50% after the incorporation of antioxidants. Some molecular interactions between polymer chains and antioxidants were confirmed by FTIR where spectra displayed a shift of the amide-III peak. Films containing caffeic acid or a caffeic-ferulic acid mixture exhibited the highest radical scavenging activity, leading to a 90% antioxidant activity at equilibrium but the release rate controlled the efficacy of the system.

In vitro and in vivo antifungal activity of chitosan-essential oils against pomegranate fruit pathogens

This study investigated the effect of chitosan combined with essential oils (cinnamon, lemon, and oregano, respectively) as edible films against the growth of three important disease-causing pathogens of pomegranate (Botrytis sp., Penicillium sp., and Pilidiella granati). Essential oils (EOs) were characterised by gas chromatography analysis and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). In vitro antifungal activity of the EOs against Botrytis sp., Penicillium sp., and Pillidiella granati was conducted on agar media inoculated with fungal spores using the inverted lid and direct contact with agar techniques. Cast films were prepared from chitosan of different (low, medium, and high) molecular weights (Mw), and assessed for use as biodegradable packaging material. Thereafter, chitosan films (medium Mw) were used in combination with 0, 10, 50 or 100gL−1 concentrations of EOs (cinnamon, lemon, and oregano) for in vitro investigation. The use of ATR-FTIR effectively discriminated the EOs based on the energy levels of the atomic bond vibrations present, as indicated by their characteristic absorption peaks. Based on GC–MS analysis of the selected EOs, 35 volatile compounds belonging to eight different chemical classes were tentatively identified. In addition, differences in chitosan Mw were found to have significant influence on the film functional properties such as colour, thickness, contact angle, and tensile strength. Based on in vitro investigation, chitosan-oregano or −cinnamon EO films with the concentration of 10gL−1 exhibited complete inhibitory effect against all three pathogens. Maximum inhibitory effects of chitosan-lemongrass films was dependent on EO concentration, with P. granati, Botrytis sp., and Penicillium sp. inhibited completely at 10, 50, and 50gL−1, respectively. Antifungal in vivo study on pomegranate fruit artificially inoculated with Botrytis sp. and treated with chitosan-oregano EO (emulsions and films), showed that both treatment methods inhibited Botrytis sp. growth. However, the inhibitory effect was higher for fruit directly dipped into the chitosan-EO emulsions as opposed to samples exposed to vapour contact via the films. This study showed that chitosan-EOs applied as edible coatings or casted films can be used to control postharvest fungal pathogens associated with pomegranate fruit.

How to Improve Properties of Functional Films by Sol–Gel Technique

How to Improve Properties of Functional Films by Sol–Gel Technique

Development and characterization of chitosan/hyaluronan film for transdermal delivery of thiocolchicoside

The objective of this study was the development of chitosan/hyaluronan transdermal films to improve bioavailability of thiocolchicoside. This approach offers the possibility to elude the first-pass metabolism and at the same time it is able to provide a predictable and extended duration of activity. Films were prepared by casting and drying of aqueous solutions containing different weight ratios of chitosan and hyaluronan and characterized for their physico-chemical and functional properties. In accordance with polymeric composition of films and, therefore, with the amount of the net charge after the complexation, films containing the same weight ratio of chitosan and hyaluronan showed lower water uptake ability with respect to films containing only one polymeric species or an excess of chitosan or hyaluronan. Moreover, the lower the hydration of the polymeric network, the lower is the drug diffusion through the films and its permeation through the skin. This study clearly confirmed that the selection of a suitable polymeric weight ratio and appropriate preparative conditions allows the modulation of film functional properties, suggesting that these formulations could be used as a novel technological platform for transdermal drug delivery.

Optimization of functionalization conditions for protein analysis by AFM

Activated vapor silanization (AVS) is used to functionalize silicon surfaces through deposition of amine-containing thin films. AVS combines vapor silanization and chemical vapor deposition techniques and allows the properties of the functionalized layers (thickness, amine concentration and topography) to be controlled by tuning the deposition conditions. An accurate characterization is performed to correlate the deposition conditions and functional-film properties. In particular, it is shown that smooth surfaces with a sufficient surface density of amine groups may be obtained with this technique. These surfaces are suitable for the study of proteins with atomic force microscopy.

Structural transformation and functional properties of vanadium oxide films after low-temperature annealing

A two-step method is offered for the synthesis of vanadium oxide films to purposely change their functional properties. Vanadium oxide films were deposited on glass and silicon substrates by using magnetron sputtering of the vanadium target at various substrate temperatures (180–500°C). During deposition, the substrate temperature predetermines structural and functional properties of the films after their following low-temperature (250–350°C) annealing. In the films deposited at low substrate temperatures (200–220°C), after low-temperature annealing there formed are flat crystallites of vanadium dioxide with lateral sizes 1 to 2μm, which provides a high thermochromic effect. In the films deposited at temperatures of 250–300°C, during the following low-temperature annealing the microcrystalline mixture of different vanadium oxides (50–150nm) is formed, which provides a high value of the thermal coefficient of resistance for these films (7%/K). The low temperature annealing practically does not change the properties of films deposited at temperatures of 450–500°C.

Impact of substrate on magnetic phase coexistence in bicritical Sm 0.53Sr 0.47MnO 3 thin films

Sm 0.53Sr 0.47MnO 3 thin films were deposited on single crystal LaAlO 3 (LAO/(001)) and SrTiO 3 (STO/(001)) substrates by DC magnetron sputtering. The θ - 2 θ and ω - 2 θ scans show that these films have very good crystallinity and the films on LAO and STO are under compressive and tensile strain, respectively. The films on LAO and STO substrates show ferromagnetic (insulator–metal) transition at T C ∼ 126 K (at T I M ∼ 128 K ) and 120 K ( T I M ∼ 117 K ), respectively. The magnetic state at T < T C is akin to cluster glass, which is formed by the presence of charge ordered-antiferromagnetic clusters in the ferromagnetic matrix. Huge drop in the resistivity at T I M and the associated hysteresis with respect to cooling and warming cycles reveal the bicritical and the first order nature of phase transition, which is also confirmed by the Banerjee criterion. The differences and similarities in the functional properties of films are explained in terms of substrate modified magnetic phase coexistence.

Functional properties of nickel cobalt oxide thin films

Cobalt–nickel oxide films of known stoichiometry (x = Ni / (Co + Ni) = 0.30–0.63) were deposited on glass slides by using a spin-coating method and were UV irradiated for 2 h. The structure and morphology of thin films evidenced nanocrystalline spinel structures. Thin films with x = 0.63–0.5 have a mixed phase structure and good sensing properties for ethanol. Thin films with x = 0.30–0.40 have a single spinel phase, are ferrimagnetic and highly conductive at 300 K and have magnetoresistance ratios of 5–8%. Four-probe measurements indicate an insulator–metal transition at temperatures slightly below ferromagnetic Curie temperature. Metallic Ni and Co particles improve thin film functional properties.

In-situ monitoring of the growth of nanostructured aluminum thin film

Metal thin film functional properties depend strongly on its nanostructure, which can be manipulated by varying nucleation and growth conditions. Hence, in order to control the nanostructure of aluminum thin films fabricated by RF magnetron sputtering, we made use of in-situ monitoring of electrical and optical properties of the growing layer as well as plasma characterization by mass and optical emission spectroscopy. The electrical conductivity and I-V characteristics were measured. The optical constants were obtained from optical monitoring based on spectral ellipsometry. The relevant models (based on one or two Lorentz oscillators and B-spline functions) were suggested to evaluate the data obtained from the monitoring techniques. The results of the in-situ monitoring were correlated with scanning electron microscope analyses. We demonstrated the monitoring was able to distinguish the growth mode in real-time. We could estimate the percolation threshold of the growing layer and control layer nanostructure. The nanostructure was effectively manipulated by RF power variation. Optical functions exhibiting plasmonic behavior in the UV range and a strong nonlinear character of I-V curves were obtained for an ultrathin Al film deposited at a lower growth rate.

Effect of crosslinking on the properties of sodium caseinate films

AbstractProtein films are used as effective lipid, oxygen, and aroma barriers at moderate relative humidity conditions. However, they perform poorly as moisture barriers. The introduction of crosslinks within or between protein chains by enzymatic or chemical modification has been proposed as an alternative means to achieving a stronger polymeric matrix structure, which would result in better functional film properties. In this article, we report the preparation and characterization of sodium caseinate (SC) films crosslinked by glutaraldehyde (GTA) or heat. The crosslinking density increased with GTA content. The thermal stability and tensile modulus and strength increased with GTA content, although films with a low crosslinking density exhibited lower properties than the uncrosslinked sample. Unexpectedly, water vapor permeability and absorption also increased with crosslinking density. The crosslinking of SC was also induced by simple heating. The resulting films showed enhanced thermal, mechanical, and barrier properties compared to the unmodified SC films and even the GTA‐crosslinked samples. GTA crosslinking was unable to reduce the high hydrophilicity of the SC films. Thermally induced crosslinking was revealed to be a valid alternative for improving the properties of SC films, without the inherent complications associated with the use of a chemical crosslinking agent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Influence of emulsifier type and content on functional properties of polysaccharide lipid-based edible films.

This study investigates the effect of different types of surfactant (glycerol monostearate, Tween 60, and Tween 80) on water vapor permeability (WVP), tensile strength (TS), percentage elongation at breaking (E), and structure of an emulsified edible film composed of cornstarch, methylcellulose, and cocoa butter or soybean oil. Factorial designs at two levels were used to analyze the effect of emulsifier (EM) and lipid content on the functional properties of film. Results showed that the effects of independent variables on WVP, TS, and E depend on surfactant and lipid type. The presence of EM significantly decreased the WVP of cocoa butter films but did not improve the barrier or mechanical properties of soybean oil-based film.

Surface roughness characterization of soft x-ray multilayer films on the nanometer scale

The soft x-ray reflectivity of multilayer films is affected by the surface roughness on the transverse nanometer scale. Scanning tunneling microscopy (STM) is an ideal instrument for providing high-lateral-resolution roughness measurements for soft x-ray multilayer films that cannot be obtained with other types of instruments on the transverse nanometer scale. The surface roughnesses of Mo/Si, Mo/C, and W/Si soft x-ray multilayer films prepared by an ion-beam-sputtering technique were measured with a STM on the vertical and transverse attributes. The film roughnesses and average spatial wavelengths added to the substrates depend on the multilayer film fabrication conditions, i.e., material combinations, number of layers, and individual layer thickness. These were estimated to lead to a loss of specular reflectivity and variations of the soft x-ray scattering angle distribution. This method points the way to further studies of soft x-ray multilayer film functional properties and can be used as basic guidance for selecting the best coating conditions in the fabrications of soft x-ray multilayer films.

Edible Packaging Films Based on Fish Myofibrillar Proteins: Formulation and Functional Properties

ABSTRACTBiopackaging materials based on fish myofibrillar proteins have been developed. The effects of protein concentration, pH, temperature and storage time before casting on the apparent viscosity of the film forming solution (FFS) were evaluated using experimental design methodology. The first objective was to determine a feasible experimental range for film‐forming. The pH and protein concentration had strong interactive effects on FFS viscosity. During FFS storage before casting, partial degradation of high molecular weight protein components led to decreased viscosity, allowing thin layer casting. In the experimental range for film‐forming, none of the conditions affected film functional properties. Standard conditions were determined at: pH 3.0, 2.0g protein/100g FFS, 25°C and 6 hr storage. The functional properties of the standard biopackaging were slightly better than those that determined for known protein‐based films, with tensile strength close to those of low density polyethylene films.