Polymer Barrier Research Articles

Novel process for preparation of metal-polymer composite membranes for hydrogen separation

In the present work, a new preparation method for metal-polymer composite materials for hydrogen separation which consist of hydride-forming intermetallic compound LaNi5 and polyethylene was developed. According to this technique, the mechanical activation of the initial powder mixtures was employed to provide good interface between the phases. A series of composite membranes with various filler concentrations was synthesized and characterized by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. The gas transport properties of the obtained materials in relation to H2, O2, N2, CO2 and CH4 were tested. The results indicate that the addition of the hydride-forming intermetallic compound to the barrier polymer leads to significantly improved selectivity with respect to hydrogen. The proposed method can be considered as a promising approach to producing of high performance composite membranes for hydrogen separation.

Influence of Implants Composition on Melatonin Release from Ethylcellulose Matrix.

Melatonin release from Ethylcellulose matrix has never been studied on the whole range of compositions. To perform a comprehensive study about the influence of the melatonin loading on its release from solid ethylcellulose implants, from both a kinetic and structural point of view. Cylindrical implants differing in their Melatonin:Ethylcellulose ratio were fabricated to cover a large range of compositions. Drug release was assayed by in vitro dissolution tests in CTAB micellar solutions. The 2D imaging of implant chemical composition during Melatonin release was performed by confocal Raman spectroscopy. FT-IR spectroscopy and Karl-Fisher technique were employed to study implants hydration. A drug radial leakage, whatever the implant composition, is imaged. The apparent diffusion coefficient, D of melatonin was evaluated considering Fickian radial diffusion: its value ranges from 2 to 6 10-12 cm2/s depending on the EC content. The variation of the characteristic drug delivery time with composition was non-monotonous and two different regimes were identified. A micellar transport of Melatonin was found. The two regimes in drug release were interpreted considering the polymer barrier effect, the initial porosity and M domains connectivity.

Dietary coated cysteamine improves antioxidant status of muscle in pig model

BackgroundMuscle fatigue and injury is common in daily life. Contracting skeletal muscles generate free radicals, which can result in oxidative damage to cellular constituents. The development of targeted antioxidants remains an important area of research in redox biology. Cysteamine is used as a novel feed additive in animal production in the form of coated cysteamine because of its antioxidant activities. However, oral formulations of cysteamine may cause adverse effects, including reduction of motor activity and generalized hemorrhage in gastrointestinal tract and kidneys. An enteric coating is a polymer barrier applied on oral medication that prevents its dissolution or disintegration in the gastric environment. The effects of coated cysteamine on oxidation in muscle and lesions in gastrointestinal (GI) mucosal were investigated in this experiment using a pig model.MethodsA total of 288 crossbred finishing pigs (Duroc × Landrace × Yorkshire) with an initial BW of 88.3 ± 0.3 kg were randomly assigned into 4 dietary groups, with 8 pens/group and 9 pigs/pen. Castrated pigs had free access to feed and drinking water, and they were fed a corn‐soybean meal diet containing 0 (control), 0.035, 0.070, or 0.140 g kg‐1 of CC for 29 days. Coated cysteamine hydrochloride contained 270 g kg‐1 cysteamine hydrochloride. At the end of experiment, one pig was randomly selected from each pen and was slaughtered by exsanguination after electrical stunning to collect samples of the longissimus dorsi muscle and GI tissue.ResultsDietary CC increased (P < 0.05) the a*(redness) and H* values, reduced (P < 0.05) the L* (lightness) value in the muscles at 48 h postmortem (P < 0.05). The contents of deoxymyoglobin (deoxyMb) was enhanced (P < 0.05) and the contents of metmyoglobin (MetMb) and malondialdehyde (MDA) were reduced (P < 0.05) in pig fed the dietary CC. Pigs fed a dietary CC of 0.035 g kg−1 had a higher a* (24 h) value in the longissimus dorsi muscles than control treatment. Pig fed the dietary CC of 0.140 g kg−1 had a higher GSH (P < 0.05) in muscle. And the mRNA expression of SOD1 was up‐regulated (P < 0.05) in the muscle of pigs fed the dietary CC of 0.140 g kg−1. Supplementation with CC in the 0.035 g kg−1 increased villus height:crypt depth ratio in ileum (P<0.01). Ileal lesion score was decreased in pigs fed a dietary CC of 0.035 g kg−1 (P<0.01).ConclusionDietary supplementation with CC could improve antioxidant status by improving GSH levels and antioxidase activity during a long recovery (48 h). Dietary supplementation with coated cysteamine hydrochloride in the 0.035 g kg−1 may improve the muscle antioxidant status without mucosal injury of GI.Support or Funding InformationWe would like to express our sincere gratitude to the National Natural Science Foundation of China (31501964; 31402088) and China Agriculture Research System (CARS‐35). The research was also funded by a research program of the State Key Laboratory of Food Science and Technology and Key Research and Development program of Shandong province (2015STS007).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Flexible and Micropatternable Triplet-Triplet Annihilation Upconversion Thin Films for Photonic Device Integration and Anticounterfeiting Applications.

Triplet-triplet annihilation upconversion (TTA-UC) has recently drawn widespread interest for its capacity to harvest low-energy photons and to broaden the absorption spectra of photonic devices, such as solar cells. Although conceptually promising, effective integration of TTA-UC materials into practical devices has been difficult due to the diffusive and anoxic conditions required in TTA-UC host media. Of the solid-state host materials investigated, rubbery polymers facilitate the highest TTA-UC efficiency. To date, however, their need for long-term oxygen protection has limited rubbery polymers to rigid film architectures that forfeit their intrinsic flexibility. This study introduces a new multilayer thin-film architecture, in which scalable solution processing techniques are employed to fabricate flexible, photostable, and efficient TTA-UC thin films containing layers of oxygen barrier and host polymers. This breakthrough material design marks a crucial advance toward TTA-UC integration within rigid and flexible devices alike. Moreover, it introduces new opportunities in unexplored applications such as anticounterfeiting. Soft lithography is incorporated into the film fabrication process to pattern TTA-UC host layers with a broad range of high-resolution microscale designs, and superimposing host layers with customized absorption, emission, and patterning ultimately produces proof-of-concept anticounterfeiting labels with advanced excitation-dependent photoluminescent security features.

Nanofiltration membranes for ionic liquid recovery

ABSTRACTNanofiltration membranes have been developed by interfacial polymerization using base PES ultrafiltration membranes. By varying the concentration of the reactive monomers present as well as the reaction conditions, the structure of the polymerized barrier layer has been modified. Here, the ability to concentrate low molecular weight sugars while allowing dissolved ionic liquids in aqueous solution to be recovered in the permeate has been investigated for application in biomass hydrolysis. The results obtained here indicate that the selectivity for 1-butyl-3-methylimidazoliumchloride (BmimCl) over glucose can be as high as 36.6. The membrane permeance was 2.31 L m−2 h−1 bar−1.

Polymer materials for prevention of postoperative adhesion.

Postoperative adhesion (POA) is a serious complication accompanied with various surgeries. Polymer material-based physical barriers have attracted a large amount of attention in POA prevention. The polymer barriers can effectively avoid the formation of fibrous tissues among normal organs by reducing the interconnection of injured tissues. In this review, specific features of the natural and synthetic polymer materials for application in POA prevention were presented, and the possible prospects were predicted. All in all, our work can provide inspiration for researchers to choose proper polymer materials for preclinical and even clinical anti-adhesion studies.

No Sting Barrier Film to Protect Skin in Adult Patients: Findings From a Scoping Review With Implications for Evidence-Based Practice.

In the industrialized world, approximately 1-1.5% of the population has received treatments for skin lesions. In the 1990s, a polymeric barrier film called the No Sting Barrier Film (NSBF) was developed as an alternative to petrolatum-based ointments and zinc oxide formulas. To date, few studies have explored the effectiveness of NSBF in protecting skin integrity. To map the methods, fields and outcomes used to produce evidence on NSBF effectiveness. A scoping review was performed in 2015. A search strategy for identifying relevant studies was designed and performed. Systematic reviews, meta-analyses, randomized controlled trials, controlled clinical trials, and comparative studies for all types of interventions were included; research conducted in any clinical context was eligible for inclusion. Studies were selected by two reviewers; data extraction and analysis also was performed by two reviewers and disagreements were discussed. Six studies were included. NSBF's potential as a skin protector was investigated with respect to (a) chronic wounds (pressure ulcers or vascular leg ulcers); (b) urinary or fecal incontinence; and (c) post-mastectomy irradiation. The principal clinical outcomes investigated were, respectively: (a) wound healing, wound exudates and erythema control; (b) incidence of incontinence-associated dermatitis and skin reactions; and (c) intensity of pruritus and skin reactions. Pain and comfort were measured in all clinical applications. The main process outcomes investigated were: (a) ease of application, (b) application and removal time, and (c) costs. Zinc oxide and petroleum formulations were the most common comparison interventions in research on chronic ulcers and incontinence; sorbolene cream and topical corticosteroids were the most frequent comparisons in the context of post-mastectomy irradiation. NBSF may be used for peri-wound skin protection in patients with chronic wounds, with urinary or fecal incontinence and for women undergoing post-mastectomy irradiation. However, more robust experimental studies are needed in all clinical fields where NBSF is applied.

On-demand Antimicrobial Treatment with Antibiotic-Loaded Porous Silicon Capped with a pH-Responsive Dual Plasma Polymer Barrier.

Chronic wounds are a major socio-economic problem. Bacterial infections in such wounds are a major contributor to lack of wound healing. An early indicator of wound infection is an increase in pH of the wound fluid. Herein, we describe the development of a pH-responsive drug delivery device that can potentially be used for wound decontamination in situ and on-demand in response to an increase in the pH of the wound environment. The device is based on a porous silicon film that provides a reservoir for encapsulation of an antibiotic within the pores. Loaded porous silicon is capped with dual plasma polymer layers of poly(1,7-octadiene) and poly(acrylic acid), which provide a pH-responsive barrier for on-demand release of the antibiotic. We demonstrate that release of the antibiotic is inhibited in aqueous buffer at pH 5, whereas the drug is released in a sustainable manner at pH 8. Importantly, the released drug was bacteriostatic against the Pseudomonas aeruginosa wound pathogen. In the future, incorporation of the delivery device into wound dressings could potentially be utilized for non-invasive decontamination of wounds.

Facile and controllable synthesis of iron nanoparticles directed by montmorillonite and polyvinylpyrrolidone

Porous host-hybridized metal nanoparticles are of great potential in sorption and catalysis related processes. The objective of this study was to synthesize property-controllable iron nanoparticles in montmorillonite and polyvinylpyrrolidone involved borohydride reduction system. In this system, mixed primary and secondary iron nanoparticles were readily generated. These resulting nanoparticles displayed an α-Fe@iron-oxide@polyvinylpyrrolidone core-double-shell architecture, in which the oxide shells protect the α-Fe cores from thorough oxidation in essential. In hybridization process, a polymer barrier was developed on the clay mineral surfaces. Due to the barrier-related steric hindrances and/or the alkaline pH-derived electrostatic repulsions, the clay mineral particles built a card-house flocculation structure, which can be converted to a semi-card-house form in dry products by suitable washing and drying treatments. The binding of the polymer to the iron and clay mineral surfaces would be mainly through hydrogen bonding. In general, the card-house pores and polymer layers made the hybridized iron nanoparticles much smaller and more dispersed than their bare counterparts. Specifically, by adjusting the molar mass and concentration of the polymer and the reductant amount, the hybridized iron nanoparticles could be further optimized. This synthesis route is carried out in situ under ambient temperature and atmosphere, greatly simplifying the process for iron nanoparticles preparation.

Graphene Oxide/Polyimide Nanocomposites for Gas Barrier Applications

Polymeric films for gas barrier applications such as food packaging and electronic devices have attracted great interest due to their cheap, light and easy processability among gas barrier materials. Especially in electronic devices, extremely low gas permeance is necessary for maintaining the device performance. However, current polymeric barrier films still suffer from relatively high gas permeance than other materials. Therefore, there have been strong needs to enhance the gas barrier performance of polymeric barrier films while keep their own advantages. Recently, graphene is highlighted as a 2D-layered material for gas barrier applications. However, owing to the poor workability and difficulty to produce in engineering scale, graphene oxide (GO) is on the rise. GO consists of oxygen-containing functional groups on surface with intrinsic 2D-layered structure and high aspect ratio, and it can be well-dispersed in aqueous polar solvents like water, resulting in scalable mass production. Here, we prepared GO incorporated polyimide (PI) nanocomposites. PI is widely used barrier polymer with high mechanical strength and thermal and chemical stability. We demonstrated that PI/GO nanocomposites could perform as a gas barrier. Furthermore, surfactants (Triton X-100 (TX) and Sodium deoxycholate (SDC)) are introduced to enhance the gas barrier performance by improving the degree of dispersion of GO in PI matrix. As a result, TX enhanced the gas barrier performance of PI/GO nanocomposites which is similar to predicted value. This finding will provide new insight to polymer nanocomposites for gas barrier applications.

Delivery Systems for Low Molecular Weight Payloads: Core/Shell Capsules with Composite Coacervate/Polyurea Membranes.

Composite polyurea/coacervate core/shell capsules are formed by coupling associative biopolymer phase separation with interfacial polymerization. They combine the excellent chemical stability of synthetic polymer barriers with the strong adhesive properties of protein-based complex coacervates, inspired by biological underwater glues. To encapsulate volatile oil droplets, a primary coacervate hydrogel capsule is formed by a protein and weak polyanion and is reinforced with a polyurea membrane synthesized in situ at the interface between the coacervate and the oil core. The polyurea layer provides an excellent permeability barrier against diffusion of small volatile molecules while the coacervate portion of the shell enhances adhesion on the targeted substrate.

Binding affinity between small molecules in solvent and polymer film using molecular dynamics simulations

Quantifying the binding affinity of small molecules to a polymeric film is very important in understanding the adsorption phenomenon in food industry. Here we present a model based on molecular dynamics simulations in conjunction with the Metadynamics method to reconstruct the free energy barrier for desorption of small molecules from a polymer surface. We use this technique to find the binding affinity of five small binder molecules (C8, C9, C10, Eugenol and d-limonene) to a polymeric film in water solvent that is primarily due to the van der Waals, hydrogen bonding and electrostatic interactions. It is found that the small molecule binding is a spontaneous process, the binding affinity is affected by their molecular structure and polarity, the aldehydes (C8, C9, C10) have much higher affinity than the Eugenol and the d-limonene, the binding affinity increases with a rise in temperature, and the aldehydes show higher temperature sensitivity than the Eugenol and the d-limonene. These findings suggest the possibility of using the binding affinity, especially the binding free energy, to guide the design and selection of polymeric barrier materials.

Electromechanically Actuated Multifunctional Wireless Auxetic Device for Wound Management.

The design and fabrication of a wound healing device for chronic wounds, with multiple functions for controlled drug delivery and exudate removal, has been described in this paper. The structural features have been machined and modified through laser cutting in a biocompatible polymer cast. Miniaturized versions of electronically actuated (lead-screw and pulley) mechanisms are used for the specific purpose of controlled drug delivery. These mechanisms have been studied and tested, being controlled through a microcontroller setup. An auxetic polymeric barrier membrane has been used for restricting the drug quantities administered. Drug delivery mechanisms are powered wirelessly, through an external, active RF component; this communicates with a passive component that is buried inside the wound healing device. The exudate removal efficiency of the device has been assessed through several simple tests using simulated wound exudate. It has been found that reasonably precise quantities of drug dosages to be administered to the wound site can be controlled through both drug delivery mechanisms; however, the lead-screw mechanism provides a better control of auxetic barrier membrane actuation and hence controlled drug delivery. We propose that this device can have potential clinical significance in controlled drug delivery and exudate removal in the management of chronic wounds.

Study of the mechanisms of barrier discharge development in the needle–plane system

The dielectric barrier discharge (DBD) was studied in three experimental configurations: “needle–polymer barrier–plane”, “needle–submillimeter air gap–polymer barrier–plane,” and“needle–submillimeter air gap–metal disk–polymer barrier–plane”. In the first case, only the DBD surface phase occurred (i.e., surface discharge), in the second case both surface and volume phases took place (i.e., typical DBD), and in the third case only the volume phase occurred (i.e., air–gap breakdown). A polyethylene terephthalate film 100 μm thick was used as a barrier. The discharge voltage, the discharge current pulse, the transferred charge, and the spatial distribution of the surface charge density were measured during the experiments. It was experimentally shown that the surface phase of the DBD has a substantial impact on the whole discharge process. The data indicate that the placement of a metal disk with a floating potential on the barrier surface causes the initiation of an atmospheric pressure glow discharge.

Preparation of Polymeric Micelles of Poly(Ethylene Oxide-b-Lactic Acid) and their Encapsulation With Lavender Oil

Nanoparticles comprised of the poly(ethylene oxide)-b-poly (lactic acid) diblock copolymer (PEO-b-PLA) with and without the incorporation of lavender oil were prepared by nanoprecipitation. Diblock copolymers based on a fixed PEO block (5KDa) and two different PLA segments (4.5 or 10KDa) were used. The morphology, encapsulation efficiency, essential oil-polymer interaction and the release kinetics of the active agent in the nanoparticles, were evaluated. The hydrodynamic radius of the nanoparticles determined by light scattering was affected by the size of the poly(lactic acid) (PLA) block. The lavender essential oil encapsulation efficiency (at a concentration of 0.4 µL mL-1) determined by UV-VIS spectroscopy was in the range of 70-75%. The in vitro release suggests that the polymeric barrier is able to control the oil release.

Protecting and preserving clear barrier layers for flexible packaging materials In-line thermal evaporation of organic topcoat layer

The end market for transparent flexible barrier films is larger than for metallized films. Presently, the market is still dominated by polymeric barrier layers but the used chemicals may be harmful for the environment. An alternative would be transparent thin layers deposited by vacuum deposition techniques using reactive processes. Ceramic materials like silicon oxide or aluminum oxide are used having a film thickness of just ∼10 nm, a coating uniformity of +/−5% across and along the film at a barrier performance below 2.0 sccm/m2d for oxygen transmission rate (OTR) and below 1.0 g/m2d for water vapor transmission rate (WVTR) on PET substrates. In this paper, details will be provided about the deposition processes for these barrier layers using thermal evaporation, plasma-assisted thermal evaporation as well as deposition by electron beam evaporation. An important factor for these high barrier transparent coatings is also to withstand the downstream processes in the whole packaging stream like slitting, lamination, printing etc. One solution is to protect the barrier layers by a Topcoat. For example, off-line deposition of lacquers is used in field but the market penetration is low due to high process and material costs. An in-situ Topcoat deposition is a smart solution to overcome this issue saving time and costs. Such an approach will be also described in the presentation and the impact on the performance of the final package will be discussed.

Lipid transfer proteins: classification, nomenclature, structure, and function.

The non-specific lipid transfer proteins (LTPs) constitute a large protein family found in all land plants. They are small proteins characterized by a tunnel-like hydrophobic cavity, which makes them suitable for binding and transporting various lipids. The LTPs are abundantly expressed in most tissues. In general, they are synthesized with an N-terminal signal peptide that localizes the protein to spaces exterior to the plasma membrane. The in vivo functions of LTPs are still disputed, although evidence has accumulated for a role in the synthesis of lipid barrier polymers, such as cuticular waxes, suberin, and sporopollenin. There are also reports suggesting that LTPs are involved in signaling during pathogen attacks. LTPs are considered as key proteins for the plant’s survival and colonization of land. In this review, we aim to present an overview of the current status of LTP research and also to discuss potential future applications of these proteins. We update the knowledge on 3D structures and lipid binding and review the most recent data from functional investigations, such as from knockout or overexpressing experiments. We also propose and argument for a novel system for the classification and naming of the LTPs.

Inhibition of postsurgical adhesions by methylene blue-loaded nanofibers versus cast film matrices

In the quest for barrier membranes for the prevention of post-surgical tissue adhesions, polymer matrices may provide a platform of biomaterials with versatile properties. However, the relationship between the anti-adhesion effects of different polymer matrices and their physicochemical and structural properties is not yet adequately understood. In a preclinical study using a rat cecum model, we directly compared the anti-adhesion potential of polyhydroxybutyrate (PHB) electrospun nanofibrous versus cast film matrices loaded with methylene blue (MB) as antioxidant adhesion inhibitor. PHB retained MB presumably forming MB-bioactivated matrices. In the preclinical study, quantitative morphologic assessment in addition to histopathologic and SEM examinations 14 days post-surgery indicated that plain PHB NFs and MB-PHB NFs, moderately enhanced cecal wall healing and inhibited adhesion formation. In contrast, reshaping PHB as cast films, significantly enhanced healing, reduced adhesion bands and prevented inter-visceral adhesions. Cast films also inhibited tissue attachment to the matrix recovered 14 days post-surgery. Both PHB matrix types reduced tissue inflammation. Despite tissue anti-adhesion potential of individual matrix components, modulation of the micro-architectural properties generated polymer barriers with varying tissue anti-adhesion and healing potentials, the MB-loaded cast film achieving the best outcome.

Functional Barrier Performance of a Polyamide-6 Membrane Towards n -Alkanes and 1-Alcohols

Polymeric barrier membranes are widely used in the food packaging area. So-called functional barriers prevent the packed food from contamination of permeants from the environment or from other packaging components. Aim of the study was to determine barrier properties of non-polar n-alkanes (n-pentane up to n-tetradecane) and polar 1-alcohols (1-propanol to 1-octanol) of a 12 µm biaxially oriented PA6 film at temperatures between 70°C and 100°C. From the experimentally determined lag times, the diffusion coefficients DP as well as the partition coefficients K of the investigated permeants were calculated. From the correlation between the molecular volume V and the diffusion coefficients DP, the lag times for lower temperatures can be predicted for temperatures between 20°C and 70°C. In conclusion, the investigated 12 µm PA6 film is a sufficient barrier towards organic compounds. The permeation of substances with molecular volumes above 200 A3 is negligible for a shelf life of three years and temperatures below of 60°C. These storage conditions are sufficient for nearly all kinds of food packaging applications. Copyright © 2016 John Wiley & Sons, Ltd.

A new method to predict the effective diffusion coefficient of gases and vapors in polyurethane/clay nanocomposite membranes

Polymer/clay nanocomposite (PCN) membranes are useful as barrier materials to reduce the permeability of gases and vapors through polymer materials. Extensive studies have focused on theoretical prediction of the effective diffusion coefficients based on the clay fraction and distribution within the polymer matrix. However, existing models are based on highly idealized geometries of the PCN membranes, and are not in agreement with experimental data as a consequence. A simple and novel numerical method based on a two-dimensional representation of the barrier membrane is developed to predict gas permeability in PCN. Employing Transmission Electron Microscopy (TEM), the nano-structure of PCN is captured and transformed into mathematical morphology data. Based on the image matrix, the barrier property of PCN was numerically modelled and generally agrees well with experimental measurements from the literature for volatile organic compounds. Because the geometry of barrier polymers can be easily captured by TEM, the proposed method should be applicable to different PCN membranes to quickly estimate the barrier properties for gases and vapors.