Temperature Responsive Copolymers Films of Polyether and Bio-Based Polyamide Loaded with Imidazolium Ionic Liquids for Smart Packaging Applications.

Temperature-responsive materials are highly interesting for temperature-triggered applications such as drug delivery and smart packaging. Imidazolium Ionic Liquids (ILs), with a long side chain on the cation and a melting temperature of around 50 °C, were synthetized and loaded at moderate amounts (up to 20 wt%) within copolymers of polyether and a bio-based polyamide via solution casting. The resulting films were analyzed to assess their structural and thermal properties, and the gas permeation changes due to their temperature-responsive behavior.

Polyether Block Amide as Host Matrix for Nanocomposite Membranes Applied to Different Sensitive Fields.

The cornerstones of sustainable development require the treatment of wastes or contaminated streams allowing the separation and recycling of useful substances by a more rational use of energy sources. Separation technologies play a prominent role, especially when conducted by inherently environmentally friendly systems such as membrane operations. However, high-performance materials are more and more needed to improve the separative performance of polymeric materials nanocomposites are ideally suited to develop advanced membranes by combining organic polymers with suitable fillers having superior properties.

A Review of the Recent Progress in the Development of Nanocomposites Based on Poly(ether--amide) Copolymers as Membranes for CO Separation.

An inspiring challenge for membrane scientists is to exceed the current materials' performance while keeping the intrinsic processability of the polymers. Nanocomposites, as mixed-matrix membranes, represent a practicable response to this strongly felt need, since they combine the superior properties of inorganic fillers with the easy handling of the polymers. In the global strategy of containing the greenhouse effect by pursuing a model of sustainable growth, separations involving CO are some of the most pressing topics due to their implications in flue gas emission and natural gas upgrading.

EVA Films Loaded with Layered Double Hydroxide (LDH) Modified with Methacrylic Anion: Effect of the Nanohybrid Filler on the Photodegradation Phenomena.

The photo-oxidative studies of ethylene vinyl acetate copolymer (EVA) matrix, filled with Layered Double Hydroxide (LDH) modified with methacrylic anion (MA), were herein reported, together with gas permeation tests. The formulation of nano-hybrid LDHs was characterized using X-ray diffractometry (XRD) and thermogravimetric analysis (TGA), demonstrating the partial intercalation of the 30% of MA anion between the LDH's galleries. The as-modified filler was introduced into an EVA matrix by mechanical milling, producing free-standing films subjected to accelerated aging.

Hollow Fiber Polyimide Membranes Prepared in a Triple Orifice Spinneret: Effect of a Reduced Water Activity in the Bore Fluid on the Gas Separation Performance.

Polyimide-based hollow fibers were spun using a triple orifice spinneret in order to apply them in gas separation. The membrane structure was tailored producing a porous external layer and a thin internal skin layer, that controlled the gas transport. The measurement of gas permeation rates and the morphological analysis were combined to obtain information on the performance of the membranes.

Effect of Bridgehead Methyl Substituents on the Gas Permeability of Tröger's-Base Derived Polymers of Intrinsic Microporosity.

A detailed comparison of the gas permeability of four Polymers of Intrinsic Microporosity containing Tröger's base (TB-PIMs) is reported. In particular, we present the results of a systematic study of the differences between four related polymers, highlighting the importance of the role of methyl groups positioned at the bridgehead of ethanoanthracene (EA) and triptycene (Trip) components. The PIMs show BET surface areas between 845-1028 m g and complete solubility in chloroform, which allowed for the casting of robust films that provided excellent permselectivities for O/N, CO/N, CO/CH and H/CH gas pairs so that some data surpass the 2008 Robeson upper bounds.

Effect of Physical Aging on Gas Transport in Asymmetric Polyimide Hollow Fibers Prepared by Triple-Orifice Spinneret.

The systematic evaluation of the gas transport properties related to differences in the history of the samples is a useful tool to appropriately design a membrane-based gas separation system. The permeation rate of six pure gases was measured over time in asymmetric hollow-fiber (HF) samples, that were prepared according to the non-solvent-induced phase separation in different operation conditions, in order to identify their response to physical aging. Four types of HFs having a different structure were analyzed, comparing samples spun in a triple-orifice spinneret to HFs prepared using a conventional spinneret.

Enhancing Gas Permeation Properties of Pebax 1657 Membranes via Polysorbate Nonionic Surfactants Doping.

Composite membranes were prepared by co-casting, incorporating two nonionic surfactants in a poly(ether--amide), Pebax 1657 up to 50 wt %. These polysorbate nonionic surfactants contain many ethylene oxide units and are very CO-philic agents; thereby, they can be exploited as membrane additives for gas separation involving carbon oxide. Dynamic light scattering analysis proved a higher stability of additionated Pebax 1657 solutions with respect to those containing only the copolymer.

Effect of the Post-Spinning Solvent Exchange on the Performance of Asymmetric, Polyimide Hollow Fibers Prepared by Using a Triple-Orifice Spinneret.

Hollow fibers (HFs) are widely applied in different membrane operations, particularly in gas separation. The present work investigates the effect of post-spinning treatment on the gas transport properties of polyimide-based HFs. The membranes were spun by using both a conventional spinneret and a triple-orifice spinneret.

Ball Milling to Produce Composites Based of Natural Clinoptilolite as a Carrier of Salicylate in Bio-Based PA11.

Antimicrobial packaging systems are recognized as effective approaches to prolong food shelf life. In this context, Bio-based PA11 loaded with a food-grade zeolite were prepared using ball milling technology in the dry state. Zeolite was filled with sodium salicylate, as an antimicrobial agent, and incorporated into the polymer matrix (~50 wt % of salicylate) at different loadings (up to 10 wt %).

Influence of the Preparation Method and Photo-Oxidation Treatment on the Thermal and Gas Transport Properties of Dense Films Based on a Poly(ether-block-amide) Copolymer.

Dense films based on the hydrophobic Pebax2533 were prepared by using solution casting in different solvents as well as compression molding and subjected to photo⁻aging under ultraviolet (UV) irradiation. The influence of the preparation method, including the casting solvents, as well as the UV irradiation time selected to treat the samples, were evaluated in terms of permeation rates of pure gases (CO₂, N₂, O₂, CH₄, He, and H₂). The transport data were correlated with the microstructure and surface properties by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), as well as water contact angle measurements.

Polymer ultrapermeability from the inefficient packing of 2D chains.

The promise of ultrapermeable polymers, such as poly(trimethylsilylpropyne) (PTMSP), for reducing the size and increasing the efficiency of membranes for gas separations remains unfulfilled due to their poor selectivity. We report an ultrapermeable polymer of intrinsic microporosity (PIM-TMN-Trip) that is substantially more selective than PTMSP. From molecular simulations and experimental measurement we find that the inefficient packing of the two-dimensional (2D) chains of PIM-TMN-Trip generates a high concentration of both small (<0.

The influence of few-layer graphene on the gas permeability of the high-free-volume polymer PIM-1.

Gas permeability data are presented for mixed matrix membranes (MMMs) of few-layer graphene in the polymer of intrinsic microporosity PIM-1, and the results compared with previously reported data for two other nanofillers in PIM-1: multiwalled carbon nanotubes functionalized with poly(ethylene glycol) (f-MWCNTs) and fused silica. For few-layer graphene, a significant enhancement in permeability is observed at very low graphene content (0.05 vol.

Carbon nanotube- and carbon fiber-reinforcement of ethylene-octene copolymer membranes for gas and vapor separation.

Gas and vapor transport properties were studied in mixed matrix membranes containing elastomeric ethylene-octene copolymer (EOC or poly(ethylene-co-octene)) with three types of carbon fillers: virgin or oxidized multi-walled carbon nanotubes (CNTs) and carbon fibers (CFs). Helium, hydrogen, nitrogen, oxygen, methane, and carbon dioxide were used for gas permeation rate measurements. Vapor transport properties were studied for the aliphatic hydrocarbon (hexane), aromatic compound (toluene), alcohol (ethanol), as well as water for the representative samples.

Enhancement of CO Affinity in a Polymer of Intrinsic Microporosity by Amine Modification.

Nitrile groups in the polymer of intrinsic microporosity PIM-1 were reduced to primary amines using borane complexes. In adsorption experiments, the novel amine-PIM-1 showed higher CO uptake and higher CO/N sorption selectivity than the parent polymer, with very evident dual-mode sorption behavior. In gas permeation with six light gases, the individual contributions of solubility and diffusion to the overall permeability was determined via time-lag analysis.

Triptycene induced enhancement of membrane gas selectivity for microporous Tröger's base polymers.

A highly gas permeable polymer with exceptional size selectivity is prepared by fusing triptycene units together via a poly-merization reaction involving Tröger's base formation. The extreme rigidity of this polymer of intrinsic microporosity (PIM-Trip-TB) facilitates gas permeability data that lie well above the benchmark 2008 Robeson upper bounds for the important O2 /N2 and H2 /N2 gas pairs.