Moisture Barrier Characteristics Research Articles

Highly conductive and flexible transparent hybrid superlattices with gas-barrier properties: Implications in optoelectronics

Transparent electrodes and passivation layers find extensive application in optoelectronic devices such as light-emitting diodes, solar cell. Integrating transparent conductive and gas diffusion barrier layers into a unified component holds promise for enhancing device performance and cost-effectiveness. However, research on these dual-function materials remains relatively scarce. Here, we introduce an innovative hybrid superlattice composed of ZnO and self-assembled monolayers, designed to function simultaneously as transparent conductive and gas diffusion barrier. Fabricated using low-temperature atomic layer deposition and molecular layer deposition techniques, the hybrid superlattice exhibited robust electric conductivity (surpassing 1400 S cm-1), exceptional moisture barrier characteristics (water vapor transmission rate < 4 × 10-7 g m-2 day-1), and remarkable flexibility. We systematically investigated the significant electrical improvement, attributing it to the formation of a well-defined amorphous/crystalline phase-composite structure in the ZnO nanolayer. Moreover, the organic layers in the superlattice enhance resilience against environmental degradation and mechanical deformation by forming a multilayered structure that effectively decouples defects in the underlying layers. These compelling features position the hybrid superlattice as a promising candidate for transparent conductive gas diffusion barriers, with diverse applications in emerging optoelectronics.

Food packaging composite film based on chitosan, natural kaolinite clay, and Ficus. carica leaves extract for fresh-cut apple slices preservation

The problem of environmental plastic contamination is one of the most serious issues facing our world today. The majority of the packaging materials used to preserve food are made of plastic which is considered an environmental issue. Natural kaolinite clay (KC) and Ficus leaf extract (FLE) were combined with chitosan in this work to create a novel antioxidant and biodegradable food packaging film. Chitosan/KC/FLE film was compared to chitosan film, Chitosan/KC, and Chitosan/FLE films in terms of structural, physical, and functional aspects. The addition of FLE and/or KC significantly improved the light and moisture barrier characteristics, mechanical properties, and antioxidant capabilities of chitosan film. Moreover, KC addition had a remarkable impact on the water vapor permeability and the biodegradability of the chitosan film. Because of the synergistic action of FLE and KC, the Chitosan/KC/FLE film delivered strong barrier and antioxidant capabilities. Furthermore, Chitosan/KC/FLE film was tested as packaging material on fresh-cut apple slices and demonstrated good food preservation regarding the weight loss, browning index, and total phenolic content of the fruit. According to our findings, Chitosan/KC/FLE film might be employed as a possible food packaging material in the food industry.

Fabrication and Characterization of the Barrier Film Having Excellent Moisture Barrier Characteristics Using Polysilazane.

Organic solar cell and OLED display devices are very sensitive to moisture, which leading to a fast degradation by the exposure to moisture and oxygen in the air. Therefore, in order to enhance the stability of the devices, a barrier film having WVTR (Water Vapor Transmission Rate) of 10-4 to 10-6 g/m²/day is required. In order to prepare the barrier film with excellent moisture blocking characteristics, perhydro polysilazane (PHPS) is used, which is developed to prepare an insulating film for semiconductors. Also a catalyst is added to lower the curing temperature to 100 °C or less. The result shows that the polysilazane is cured and converted to SiO₂ under 100 °C in 30 min. WVTR of the polysilazane coated film is estimated to be 2.1×10-2 g/m²/day. In addition, when the inorganic layer such as SiO₂ and Al₂O₃ is deposited on the planarization layer, the film shows excellent moisture blocking characteristics having WVTR to be 7.9×10-5 g/m²/day.

A new approach in the hydrophobic modification of polysaccharide-based edible films using structured oil nanoparticles

This work aimed to study the effect of structured oil nanoparticles (SONs) for improving the hydrophobicity of polysaccharide-based edible films as a novel modification approach. SONs were fabricated from sunflower oil (SFO) using ethyl cellulose or monoglyceride as gelator. Farsi gum (FG) was selected as a model polysaccharide to develop edible films. The physicochemical, mechanical, thermal, and morphological properties of FG-based films incorporated with different concentrations (0%, 0.5 %, and 1% (w/w)) of SONs were compared with those of SFO-free (control) and SFO-incorporated FG films. Irrespective of the physical nature of added oil, the water vapor permeability, solubility, swelling ability, and surface hydrophilicity of FG films incorporated with SONs or SFO were significantly decreased. The SFO was more effective than the SONs in improving some hydrophobic properties; however, the flocculation of SFO droplets decreased the water vapor barrier properties. Incorporating SONs resulted in a compact and more uniform surface morphology, while a higher roughness and surface irregularity were observed after modification with SFO. The modified films prepared by incorporating SONs showed appropriate tensile strength and higher flexibility than control film, while those incorporated with liquid SFO droplets were too sticky and stretchy to be subjected to the tensile forces. The thermal stability of modified films was enhanced after incorporating SONs. The results indicated that the key properties of FG films were better improved by incorporating SONs than liquid oil droplets. Therefore, the SONs can be considered as an appropriate candidate for developing novel edible food packaging materials with high moisture barrier characteristics.

Transparent and super-gas-barrier PET film with surface coated by a polyelectrolyte and Borax

Thin films of polyacrylic acid (PAA), 4,4‘-diphenylmethane diisocyanate (MDI) and borax were separately grown on a poly (ethylene terephthalate) (PET) film to afford a transparent film material with super gas barrier performance. Unlike electrostatic interactions or clay-loaded barrier thin films, which were easily peeled when subjected to exoteric force, excellent peel strength was obtained due to the formation of high density urethane chemical bonds. The gas vapor barrier value is dramatically decreased to the detection limit of commercial instrumentation (<0.005 cc/m2/day). These outstanding performances are attributed to the reaction between sodium metaborate and PAA, which is confirmed using online infrared radiation (IR) and X-ray photoelectron spectroscopy (XPS). The XPS of the multilayer film revealed that borax can permeate the PAA thin layer to completely crosslink the carboxyl group of PAA. The gas barrier properties are obviously improved by the permeating borax solution. In particular, compared to commercial PET film, the oxygen transmission rate (OTR) is reduced from 75 to <0.005 cc/m2/day. Moreover, the OTR value is almost same as that of poly(ethylene-co-vinyl alcohol) (EVOH) film, which is currently the best gas barrier plastic. Therefore, the PET/MDI/PAA/borax composite films show great potential for various packaging materials due to their excellent oxygen and moisture barrier characteristics, as well as other performance. By simply coating a thin layer of 4,4’-diphenylmethane diisocyanate, polyacrylic acid and borax on the surface of PET film, a transparent PET film with extremely low gas vapor barrier value can be obtained. The oxygen transmission rate can be dramatically decreased to the detection limit of commercial instrumentation (<0.005 cc/m2/day).

Biodegradable poly(propylene carbonate)/layered double hydroxide composite films with enhanced gas barrier and mechanical properties

Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides (LDHs) were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH (OLDH) in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A series of poly(propylene carbonate) (PPC)/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient (OP) and water vapor permeability coefficient (WVP) is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.

Epoxy-organoclay nanocomposites: morphology, moisture absorption behavior and thermo-mechanical properties

The morphology and moisture barrier characteristics are studied of epoxy-based nanocomposites reinforced with layered silicates. Two different types of organoclay, including the quaternary alkylamine modified montmorillonite (KH-MT) and the octadecylamine modified montmorillonite (I30P), were studied. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicate that the I30P system exhibited a large increase in interlayer d -spacing from 3.39 mm to over 8 nm during the curing process, whereas the KH-MT system showed negligible changes in reflection angle and d -spacing, with the final interlayer distance of 3.39 nm after cure. The moisture absorption behaviour was different for different organoclays: the moisture absorption rate was similar for the neat polymer and the KH-MT system, which could be fitted to Fick's second law. The moisture absorption rate of the I30P system was much lower than the two systems, which was predicted using a non-Fickian model based on the ID Langmuirian solution. The deviation from the Fickian diffusion for the latter system is associated with exfoliated morphology and more uniform dispersion of clay particles, which altered the diffusion path of water molecules in the nanocomposite. The moisture diffusivity of nanocomposites in general decreased with increasing clay content, the reduction being more pronounced for the I30P system. The normalized permeability also showed a systematic degradation with increasing clay content, which agrees well with the prediction based on the tortuous path model.

Moisture barrier characteristics of organoclay–epoxy nanocomposites

The moisture diffusion and barrier characteristics of epoxy-based nanocomposites containing organoclay are investigated. The effects of different types of organoclay modified with different compatibilizers, including a quaternary alkylamine-modified montmorillonite (KH-MT), a quaternary ammonium-modified montmorillonite (Cloisite 20A) and an octadecylamine-modified montmorillonite (I30P), on moisture barrier and thermomechanical properties are specifically studied. The moisture absorption and diffusion behaviours were different depending on the type of organoclay: the moisture absorption rates of the Cloisite and I30P systems were much lower with associated lower diffusivity than the KH-MT system or the neat epoxy, due to the higher interlayer distance and more uniform distribution of organoclays, which in turn allowed a longer diffusion path of water molecules in the nanocomposite. The moisture diffusivity of nanocomposites decreased with increasing clay content for all organoclays. The corresponding moisture permeability was lower in the order of nanocomposites containing I30P, Cloisite and KH-MT organoclays. The moisture permeability showed a systematic decrease with increasing clay content, which agrees well with the prediction based on the simple tortuous path model. Increase in effective penetration path due to the very large aspect ratio of the silicate layers was responsible for the reduced moisture permeability. The glass transition temperature was much higher for the I30P nanocomposite than the neat epoxy resin, whether dry or wet condition. It decreased linearly with increasing moisture content. The CTE decreased with increasing clay content for all conditions studied.

Moisture Resistance of Plasma Enhanced Chemical Vapor Deposited Oxides Used for Ultralarge Scale Integrated Device Applications

The moisture resistance of plasma enhanced chemical vapor deposited (PECVD) oxide films used in ultralarge scale integrated (ULSI) device applications has been characterized using infrared (IR) spectroscopy. The differences in the moisture absorption characteristics between tetraethylorthosilicate (TEOS) and silane‐based PECVD oxides are presented. Our results indicate that the film thickness and the as‐deposited film stress are important factors in controlling the moisture resistance of these PECVD oxides; the deposition of these PECVD oxides using higher ratios enhances moisture resistance; the use of instead of as the oxidizing agent incorporates nitrogen as well as Si—H bonds in the film which enhance moisture resistance, and that an in situ plasma post‐treatment of PECVD films improves the moisture barrier characteristics of the these oxide films.