Confinement Effect in Multilayer Films Made from Semicrystalline and Bio-Based Polyamide and Polylactic Acid.

Bio-based multilayer films were prepared by using the innovative nanolayer coextrusion process to produce films with a number of alternating layers varying from 3 to 2049. For the first time, a semicrystalline polymer was confined by another semicrystalline polymer by nanolayering in order to develop high barrier polyamide (PA11)/polylactic acid (PLA) films without compromising thermal stability and mechanical behavior. This process allows the preparation of nanostratified films with thin layers (down to nanometric thicknesses) in which a confinement effect can be induced.

PVC/EVA-based polymer inclusion membranes with improved stability and Cr(VI) extraction capacity: Water plasticization effect.

Polymer inclusion membranes (PIMs) are far investigated for their ability to extract heavy metals and small organic compounds from aqueous media. Polyvinyl chloride (PVC) is one of the most widely used base polymers for the PIM elaboration. However, its use requires the incorporation of a relatively expensive liquid plasticizer.

Novel Ionic Conducting Composite Membrane Based on Polymerizable Ionic Liquids.

In this work, the design and characterization of new supported ionic liquid membranes, as medium-temperature polymer electrolyte membranes for fuel-cell application, are described. These membranes were elaborated by the impregnation of porous polyimide Matrimid with different synthesized protic ionic liquids containing polymerizable vinyl, allyl, or methacrylate groups. The ionic liquid polymerization was optimized in terms of the nature of the used (photo)initiator, its quantity, and reaction duration.

Novel Poly(Vinylidene Fluoride)/Montmorillonite Polymer Inclusion Membrane: Application to Cr(VI) Extraction from Polluted Water.

Novel hybrid polymer inclusion membranes (PIMs) based on poly(vinylidene fluoride) (PVDF) (polymer matrix) and Aliquat 336 (ion carrier) and containing native sodium (Cloisite Na (CNa)) and organo-modified (Cloisite 30B (C30B)) Montmorillonites were elaborated and tested for the removal of toxic Cr(VI) ions from the aqueous solution. The influence of the nanoclay incorporation on the physicochemical properties of PVDF-based PIMs was studied and the resulting membrane transport properties of the Cr(VI) ions were investigated in detail. The water contact angle measurements reveal that the incorporation of the CNa nanofiller affects the membrane wettability as less hydrophilic surface is obtained in this case-~47° in the presence of CNa as compared with ~15° for PIMs with C30B.

Enhanced water and oxygen barrier performance of flexible polyurethane membranes for biomedical application.

In order to improve water and oxygen barrier properties, the surface of two commercial medical grade polyurethane (PU) membranes (Chronoflex® AR-LT and Bionate® II) was modified by a spray deposited film of poly(ethylene-co-vinyl alcohol) (EVOH). The influence of the temperature, the deposited layer thickness and the EVOH ethylene group percentage (27%, 32%, and 44% for EVOH27, EVOH32, and EVOH44, respectively) on the barrier properties of the PU/EVOH multilayered membranes was investigated. The increase of the EVOH layer thickness leads to higher oxygen barrier properties (the highest barrier improvement factor of 412 was obtained).

Structural and Barrier Properties of Compatibilized PE/PA6 Multinanolayer Films.

The barrier performance and structural lightening of organic materials are increasingly desired and constitute a major challenge for manufacturers, particularly for transport and packaging. A promising technique which tends to emerge in recent years is that of multinanolayer coextrusion. The advantage is that it can produce multilayers made of thousands of very thin layers, leading to new properties due to crystalline morphology changes induced by confinement.

Biodegradable PLA/PBSA Multinanolayer Nanocomposites: Effect of Nanoclays Incorporation in Multinanolayered Structure on Mechanical and Water Barrier Properties.

Biodegradable PLA/PBSA multinanolayer nanocomposites were obtained from semi-crystalline poly(butylene succinate--butylene adipate) (PBSA) nanolayers filled with nanoclays and confined against amorphous poly(lactic acid) (PLA) nanolayers in a continuous manner by applying an innovative coextrusion technology. The cloisite 30B (C30B) filler incorporation in nanolayers was considered to be an improvement of barrier properties of the multilayer films additional to the confinement effect resulting to forced assembly during the multilayer coextrusion process. 2049-layer films of ~300 µm thick were processed containing loaded PBSA nanolayers of ~200 nm, which presented certain homogeneity and were mostly continuous for the 80/20 wt% PLA/PBSA composition.

The Impact of Reactive Ionic Liquids Addition on the Physicochemical and Sorption Properties of Poly(Vinyl Alcohol)-Based Films.

A new type of hybrid polymeric-based film containing 1-(1,3-diethoxy-1,3-dioxopropan-2-ylo)-3-methylimidazolium bromide (RIL1_Br) and 1-(2-etoxy-2-oxoethyl)-3-methylimidazolium bromide (RIL2_Br) reactive ionic liquids was elaborated. Poly(vinyl alcohol) (PVA)-based films with 9-33 wt % of RILs were subsequently characterized using Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and TGA-FTIR. PVA-RIL films were also studied in tensile tests, contact angle and sorption measurements.

Polyimide/Ionic Liquid Composite Membranes for Middle and High Temperature Fuel Cell Application: Water Sorption Behavior and Proton Conductivity.

Four water insoluble room-temperature protic ionic liquids (PILs) based on the -alkylimidazolium cation with the alkyl chain length from 1 to 4 and bis(trifluoromethylsulfonyl)imide anion were synthesized and their chemical structure was confirmed by the H NMR and F NMR analysis. PILs were revealed to be thermally stable up to 360 and 400 °C. At the same time, the proton conductivity of PILs was found to be dependent mostly on the temperature and, to a less extent, on the type of the cation, i.

Chronic wound healing: A specific antibiofilm protein-asymmetric release system.

Chronic infection is a major cause of delayed wound-healing. It is recognized to be associated with infectious bacterial communities called biofilms. Currently used conventional antibiotics alone often reveal themselves ineffective, since they do not specifically target the wound biofilm.

Chemically and Thermally Crosslinked PVA-Based Membranes: Effect on Swelling and Transport Behavior.

The novel poly(vinyl alcohol) (PVA)-based membranes were prepared using the two-step crosslinking approach: the chemical crosslinking of PVA using sulfosuccinic acid (SSA) (0-50 wt.%) and the thermal treatment (120-160 °C). The membrane composition and crosslinking temperature were optimized in terms of the mechanical and transport properties.

Designing Biodegradable PHA-Based 3D Scaffolds with Antibiofilm Properties for Wound Dressings: Optimization of the Microstructure/Nanostructure.

One major factor inhibiting natural wound-healing processes is infection through bacterial biofilms, particularly in the case of chronic wounds. In this study, the micro/nanostructure of a wound dressing was optimized in order to obtain a more efficient antibiofilm protein-release profile for biofilm inhibition and/or detachment. A 3D substrate was developed with asymmetric polyhydroxyalkanoate (PHA) membranes to entrap Dispersin B (DB), the antibiofilm protein.

Structure and Barrier Properties of Multinanolayered Biodegradable PLA/PBSA Films: Confinement Effect via Forced Assembly Coextrusion.

Multilayer coextrusion processing was applied to produce 2049-layer film of poly(butylene succinate-co-butylene adipate) (PBSA) confined against poly(lactic acid) (PLA) using forced assembly, where the PBSA layer thickness was about 60 nm. This unique technology allowed to process semicrystalline PBSA as confined polymer and amorphous PLA as confining polymer in a continuous manner. The continuity of PBSA layers within the 80/20 wt % PLA/PBSA layered films was clearly evidenced by atomic force microscopy (AFM).

Physicochemical properties and biological activities of novel blend films using oxidized pectin/chitosan.

Pectin has been widely used in a variety of biomedical applications. In this study, it was modified with sodium periodate as an oxidant and characterized by physicochemical methods Periodate oxidation increased the contents of dialdehyde units and carboxyl groups in pectin, and a decrease in pectin viscosity was measured. The oxidization reaction led to a significant decrease in all values of molecular weight and size (Mn, Mw, [η] and Rh) as determined by size exclusion chromatography (SEC), which allowed the selection of the oxidized pectin to be added to chitosan.

Elucidation of innovative antibiofilm materials.

It is known for roughly a decade that bacterial communities (called biofilms) are responsible for significant enhanced antibiotherapy resistance. Biofilms are involved in tissue persistent infection, causing direct or collateral damage leading to chronic wounds development and impairing natural wound healing. In this study, we are interested in the development of supported protein materials which consist of asymmetric membranes as reservoir supports for the incorporation and controlled release of biomolecules capable of dissolving biofilms (or preventing their formation) and their use as wound dressing for chronic wound treatment.

Effect of molecular structure of sulphonated polyimide membranes on water sorption.

Water sorption in sulphonated polyimides with or without ionic block structure was analysed with Feng's new dual mode model. The effect of their molecular structure that determines the chain organisation in the solid materials was analysed by using the model parameters. The model parameters Cp and A' correspond to the sorbed water molecules on the first layer close to the ionic groups and on the subsequent layers, respectively.

Thermal and mechanical properties of bio-nanocomposites reinforced by Luffa cylindrica cellulose nanocrystals.

Cellulose nanocrystals have been prepared by acid hydrolysis of Luffa cylindrica fibers. The acid-resistant residue consisted of rod-like nanoparticles with an average length an diameter around 242 and 5.2nm, respectively (aspect ratio around 46).

Water barrier properties in biaxially drawn poly(lactic acid) films.

Crystallization is among the easiest ways to improve polymer barrier properties because of the tortuosity increase within the material and the strong coupling between amorphous and crystalline phases. In this work, poly(lactic acid) (PLA) films have undergone α' thermal crystallization or different drawing processes. Although no effect of α' thermal crystallization on water permeability is observed, the drawing processes lead to an enhancement of the PLA barrier properties.

Permeation properties of poly(m-xylene adipamide) membranes.

The permeation properties of a semiaromatic polyamide, the poly(m-xylene adipamide) (MXD6), were investigated by water and carbon dioxide permeation experiments (pervaporation and gas permeation tests). Complementary microstructure informations were obtained from calorimetric measurements. Amorphous and semicrystalline MXD6 membranes were studied.

Polyepichlorhydrin membranes for alkaline fuel cells: sorption and conduction properties.

Polymer electrolytes, using a poly(epichlorhydrin-allyl glycidyl ether) copolymer as matrix, are shown to perform well in alkaline fuel cell electrolyte. An anion-conducting network is obtained by the incorporation of cyclic diamines, 1,4-diazabicyclo[2.2.