Modified Galactoglucomannans from Forestry Waste-water for Films and Hydrogels

Transparent, high gas barrier films are crucial in the medical, food, and electronic industries. The main properties required for electronic devices such as flexible displays include transmittance of >90% and oxygen transmission rates (OTRs) and water vapor transmission rates (WVTRs) of 10–3 to 10–6 cc(g) m–2 day–1. Herein, we report reduced graphene oxide (rGO)/inorganic and organic/inorganic composites coated on poly(ethylene terephthalate) (PET) film with superior oxygen and water vapor barrier properties and high transmittance. The OTR (at 23 °C, 0% relative humidity) and WVTR (at 37.8 °C, 100% relative humidity) values of the composite films (140 μm) decreased by 8 × 104 times and 6.71 × 102 times, respectively, relative to those of the PET substrate film (125 μm). The transmittance of the composite films at 550 nm was 84%, corresponding to only a 9% decrease compared to that of the PET film. Additionally, with only nanolayers of SiOxNy (100 nm) and rGO (13 nm) coating on the PET substrate, the OTR and WVTR were reduced by 2000 times and 470 times, respectively. A polyvinylidene fluoride/rGO (PVDF/rGO) layer on the SiOxNy/PET substrate showed 8.8 × 105 times lower oxygen permeability and 1.6 × 104 times lower water permeability compared to those of PVDF/rGO on the PET substrate, implying that the inorganic SiOxNy nanolayer is crucial, affording a synergistic effect toward the barrier film. The gas permeabilities of the composite films strongly depend on the design of the coating structure, rGO content, and blend ratio of PVDF and PMMA; this allows efficient control of the nanodefects of the composite film. This study shows the significance of inorganic materials and the synergistic effect of composites on barrier films, which are required for applications in organic electronic devices and packaging materials.

In this study, antioxidant biodegradable films based on pea protein and alpha-tocopherol were successfully developed by solution casting. The effect of both the homogenization conditions (rotor–stator and microfluidizer) and the relative humidity (RH) on the microstructure and physical properties (transparency, tensile, oxygen and water vapour barrier properties) of pea protein/alpha-tocopherol-based films was evaluated. The addition of alpha-tocopherol produced minimal changes in the films’ transparency, while providing them with antioxidant properties and improved water vapour and oxygen barrier properties (up to 30 % in both water vapour and oxygen permeability) when films were at low and intermediate RH. The addition of alpha-tocopherol in microfluidized films gave rise to an increase in their resistance to break and extensibility (up to 27 % in E values) at intermediate and high RH. These results add a new insight into the potential of employing pea protein and alpha-tocopherol in the development of fully biodegradable antioxidant films which are of interest in food packaging.

The fact that most composites consist of polluting synthetic materials has prompted a search for biodegradable replacements based on cellulose fibers and polycaprolactone as potential packaging materials. In this work, we developed a green, efficient approach to rendering hydrophobic polycaprolactone (PCL) compatible with hydrophilic cellulose fibers by using an ionic liquid as a nanowelding agent in the presence of zinc oxide nanoparticles (ZnONPs). Transparent biobased nanocomposite films were thus directly obtained by in situ ring-opening polymerization (ROP) of ε-caprolactone (CL) monomers onto the dissolved cellulose matrix by using the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac). [EMIM]Ac and ZnONPs were efficiently catalyzed ε-caprolactone ROP under mild conditions. Cellulose-grafted PCL nanocomposite films were obtained by adding variable amounts of CL and ZnONPs to the cellulose matrix. The maximum grafting of 40% was achieved by using 5▒wt% ZnONPs and 70% CL. FTIR spectra confirmed the presence of PCL in the nanocomposites. Also, FE-SEM revealed uniform dispersion of ZnONPs and PCL in the regenerated cellulose matrix, and trapping of nanoparticles in nanofibrils after the cellulose matrix was regenerated. X-ray diffraction (XRD) spectra showed a decreased apparent crystallinity and crystallite size. The XRD results also confirmed that the crystal properties of the nanocomposite films and an all-cellulose composite (ACC) were almost identical. The mechanical, barrier and optical properties of the nanocomposite films were significantly better than those of the ACC film by effect of the incorporation of ZnONPs and PCL especially with 5▒wt% ZnONPs and 70% CL). The nanocomposite films exhibited acceptable antioxidant activity and UV-light barrier properties, so they hold promise for used in food packaging. Nanocomposite films are in fact multifunctional materials with the potential for use in cellulose-based food packaging by virtue of their being transparent and bio-based, and possessing very good water vapor and oxygen barrier properties.

Effect of Water Vapor on the Transport Properties of Oxygen through Polyamide Packaging Materials

Properties of blends having two types of hybrid dispersed phases as laminar morphology were investigated. The hybrid dispersed phases were prepared by preblending nylon and ethylene–vinyl alcohol (EVOH) in solid state (E + N) and in melt state (E/N). Oxygen and toluene barrier properties through the hybrid-dispersed phases in low-density polyethylene (LDPE) matrix were analyzed considering the morphological changes (number and size of layers). Oxygen barrier properties of the blends of LDPE–E + N hybrid dispersed phase having separate domains of nylon and EVOH were found to be linearly dependent on EVOH composition in the blend, but toluene barrier properties of the blends exhibited negative deviation. The other hybrid dispersed phase (E/N) in LDPE matrix, having comingled dispersed phase of nylon and EVOH, exhibited positive deviations in both oxygen and toluene barrier properties. Tensile properties also showed positive deviation. Basic studies on the melt blend (E/N) of EVOH and nylon 6 showed some miscibility, which was revealed from melting point depression, and positive deviation in complex viscosity and tensile properties of the blend. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2001–2014, 1998

Edible oxygen barrier bilayer film pouches from corn zein and soy protein isolate for olive oil packaging

ABSTRACTChrysotile nanotubes (ChNTs) were synthesized under hydrothermal conditions. These synthetic nanotubes crystallographically and morphologically mimic the nanofibrils of natural white asbestos but they are considerably shorter. ChNTs containing polyimide nanocomposites were prepared by a solution mixing/casting method. Oxygen and water vapor barrier of the nanocomposite films were tested and related to the amount, dispersion, and orientation of the nanotubes. The dispersion and orientation of the nanotubes were examined by transmission electron microscopy (TEM). The nanotubes were nanodispersed and oriented in the plane of the film in the nanocomposites with up to 4.5% (vol/vol) of ChNTs leading to a gradual increase of the gas barrier. The lowest gas permeability was 60% smaller than that for the pristine polyimide film. However, with the onset of nanotube micro aggregation at larger ChNTs loadings the nanotube dispersion and orientation were compromised and oxygen barrier was reduced. The efficacy of nanotubes to enhance polymer gas barrier was discussed and compared with that by nanoplatelets. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1184–1193

Characterization of reactively sputtered permeation barrier materials on polymer substrates

A “core-shell” structure imparting both gas barrier and UV shielding properties for a PLA/ PGA/ PBS ternary blend film

Applications of cellulose nanomaterials (CNMs) have attracted increasing attention in recent years. One conceivable path lies in their commercial applications for packaging, in which their barrier properties will play an important role in determining their competiveness with conventional materials. This review critically analyzes the performance of CNMs acting as a barrier against moisture and oxygen permeation in CNM films, CNM-coated polymers and papers, and CNM-reinforced polymer composites, gives some insights into remaining challenges, and brings an overall perspective of compositing CNMs with other materials to achieve balanced properties adequate for barrier packaging. In general, CNMs are a poor moisture barrier but excellent oxygen barrier in the dry state and are still good below 65% relative humidity. The addition of CNMs can improve the oxygen barrier of the resulting polymer composites; however, neat CNM coatings and films can afford better oxygen barrier properties than dispersed CNMs in coatings and nanocomposites. The morphology and surface functionality of CNMs can be tailored to maximize the barrier performance of materials comprising them. The higher the surface charge density is of CNMs, the better is the barrier performance of coated polymers. Like other oxygen barriers such as ethylene vinyl alcohol and cellophane, the moisture sensitivity and sealability of CNMs can be improved by sandwiching them with high moisture-resistant and sealable polymers such as a polyolefin. A multilayered structure with layers of CNMs providing oxygen resistance covered by other layers of polymers providing moisture resistance and sealability might be competitive in barrier packaging markets dominated by synthetic plastics.

Two-dimensional nanocontainers with sheet structure endow epoxy resin with triple effects of oxygen barrier, anti-corrosion and corrosion inhibition

Waterborne poly(styrene‐co‐butyl acrylate) was prepared via miniemulsion polymerization in which nanoclay (Cloisite® 30B, modified natural MMT) in different concentrations was encapsulated. Scanning electron microscopy, X‐ray diffraction, and transmission electron microscopy confirmed the encapsulation and intercalated‐exfoliated structure of Cloisite® 30B within poly(styrene‐co‐butyl acrylate). The effect of nanoclay content on water vapor permeability, water uptake, oxygen permeability, thermal, and mechanical properties of thin films containing 1.5, 2.56, 3.5, and 5.3 wt % encapsulated Cloisite® 30B in poly(styrene‐co‐butyl acrylate) was investigated. The presence of encapsulated Cloisite® 30B within the polymer matrix improved tensile strength, Young's modulus, and toughness of the nanocomposites depending on the nanoclay content. Water vapor transmission rate, oxygen barrier properties, and thermal stability were also improved. The results indicated that the incorporation of Cloisite® 30B in the form of encapsulated platelets improved physicomechanical properties of the nanoclay‐polymer composite barrier films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Specific mechanical properties and molecular delivery capacities are important parameters in biomedical materials. However, in most materials, these two properties are intertwined and orthogonal adjustments of each of these properties remains difficult. In this report we propose a hydrogel design strategy that permits orthogonal adjustment of the mechanical strength and molecular delivery properties. Our strategy involves employing a double‐network hydrogel whereby the PAM network is responsible for adjusting the mechanical strength, and a CD‐laden network tunes the molecular delivery speeds taking advantage of the affinity between the diffusive molecules and the matrix. The mechanical strengths between 50 and 350 Pa were varied in the hydrogel matrix, and molecular deliveries with times varying between 200 min and 133 h were achieved. A complex hydrogel matrix permits delivery of three molecules with dramatically different release profiles. Cell culturing results show the sensitivity of the cell's response to the tuning of mechanical strength and delivery efficiency. We believe that our hydrogel matrix design concept broadens the design scope and functions of biomedical materials.

The effects of small laccase (SLAC) from Streptomyces coelicolor on the properties of whey protein isolate (WPI) films were studied. WPI was catalyze by SLAC without phenolic acid assistance. Particle size distribution results showed that some complexes with higher relative molecular weight formed in WPI samples treated with SLAC. The content of α-helixes decreased while those of β-sheets and random coils increased following SLAC treatment according to circular dichroism results. Fourier transform infrared spectral analysis suggested that some conformational changes occurred in WPI following SLAC treatment. Analysis of WPI films prepared by casting after SLAC treatment indicated that their film properties were all improved, including mechanical properties, solubility, water vapor, oxygen and carbon dioxide barrier properties, film color, light transmission, transparency and thermal properties. Compared with that of the control film, some obvious differences in the morphology of the WPI films were observed following SLAC treatment. This report demonstrates that laccase can directly catalyze protein cross-linking, which may be useful to improve the performance of protein films. In this study, SLAC was applied to WPI edible film during the film-making process. The results showed that SLAC can catalyze WPI cross-linking without phenolic acid assistance, and WPI film properties were improved after SLAC treatment. © 2018 Society of Chemical Industry.

The objective of the present study was to develop an orally disintegrating film (ODF) for a poorly water-soluble drug, phenytoin (PHT), using the cosolvent solubilization technique to achieve the amorphization of the drug, followed by the preparation of ODFs. Eleven formulations were prepared with different polymers, such as polyvinyl alcohol (PVA) and high methoxyl pectin (HMP) by the solvent casting method. The prepared films were subjected to characterization for weight variations, thickness, surface pH, disintegration time and mechanical strength properties. Then, differential scanning calorimetry, X-ray diffraction analysis and the drug release patterns of the selected films were evaluated. Among the prepared formulations, the formulation composed of 1% w/w of PVA, 0.04% w/w of sodium starch glycolate with polyethylene glycol 400, glycerin and water as cosolvents (PVA-S4) showed promising results. The physical appearance and mechanical strength properties were found to be good. The PVA-S4 film was clear and colorless with a smooth surface. The surface pH was found to be around 7.47 and the in vitro disintegration time was around 1.44 min. The drug content of the PVA-S4 film was 100.27%. X-ray diffractometry and thermal analysis confirmed the transition of phenytoin in the PVA-S4 film into a partially amorphous state during film preparation using the cosolvent solubilization approach. The resulting PVA-S4 film showed a higher dissolution rate in comparison to the film without a cosolvent. Overall, this study indicated the influence of cosolvents on enhancing the solubility of a poorly water-soluble drug and its film dissolution.