Intrinsically Porous Polymer Protects Catalytic Gold Particles for Enzymeless Glucose Oxidation

The enzymeless glucose oxidation process readily occurs on nano‐gold electrocatalyst at pH 7, but it is highly susceptible to poisoning (competitive binding), for example from protein or chloride. Is it shown here that gold nanoparticle catalyst can be protected against poisoning by a polymer of intrinsic microporosity (PIM‐EA‐TB with BET surface area 1027 m² g^?1). This PIM material when protonated, achieves a triple catalyst protection effect by (i) size selective repulsion of larger protein molecules (albumins) and (ii) membrane ion selection effects, and (iii) membrane ion activity effects. PIM materials allow “environmental control” to be introduced in electrocatalytic processes.     

Modification of activated carbon porosity by pyrolysis under pressure of organic compounds

Co-pyrolysis at relatively low temperature (673 K) and high pressure (10 MPa), using three organic compounds, was used to modify the porosity of the two ACs. The co-pyrolysis is effective for the modification of the porosity of an AC, and the efficiency depends on the organic compound used. The differences found are consequence of the chemical composition of the organic precursor. High pressure pyrolysis produces beneficial results when an organic compound that volatilizes during the preparation is used. Conducting pyrolysis at low temperature permits improved control of the porosity because the rate of gasification can be more tightly controlled.     

Preparation and characterization of activated carbon from date stones by physical activation with steam

Activated carbons are produced from wastes of Algerian date stones by pyrolysis and physical activation in the presence of water vapor into a heated fixed-bed reactor. The effect of pyrolysis temperature and activation hold time on textural and chemical surface properties of raw date stones and carbon materials produced are studied. As expected, the percentage yield decreases with increase of activation temperature and hold time. The characterization of carbon materials is performed by scanning electron microscopy (SEM). X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption (BET). Results show the presence of cellulose and hemicellulose in the raw material, and the predominance of carbon and graphite after pyrolysis. Different oxygen-containing functional groups are found in the raw material while aromatic structures are developed after pyrolysis and activation. The best specific surface area (635 m² g⁻¹) and microporous volume (0.716 cm³ g⁻¹) are obtained when the date stones are grinded, pyrolysed at 700 °C under a 100 cm³ min⁻¹ nitrogen flow and then activated under water vapor at 700 °C for 6 h.     

Cross-linking of Polymer of Intrinsic Microporosity (PIM-1) via nitrene reaction and its effect on gas transport property

Polymer of Intrinsic Microporosity (i.e. PIM-1) has been crosslinked thermally via nitrene reaction using polyethylene glycol biazide (PEG-biazide) as a crosslinker. The crosslinking temperature was optimized using TGA coupled with FT-IR spectroscopy. The dense membranes containing different ratios of PIM-1 to PEG-biazide were cast from chloroform solution. Crosslinking of PIM-1 renders it insoluble even in excellent solvents for the uncrosslinked polymer. The resulting crosslinked membranes were characterized by FT-IR spectroscopy, TGA and gel content analysis. The influence of crosslinker content on the gas transport properties of PIM-1, its density and fractional free volume (FFV) were investigated. Compared to the pure PIM-1 membrane, the crosslinked PIM-1 membranes showed better gas separation performance especially for CO₂/N₂, CO₂/CH₄ and propylene/propane (C₃H₆/C₃H₈) gas pairs and as well as suppressed penetrant-induced plasticization under high CO₂ pressure.     

Transport of Moist Air Through Microporous Polyolefin Films

Abstract

The technological revolution and busy schedule compel human society to search for better civic amenities. This leads to the use of modern personal care goods such as disposable diapers and sanitary napkins. Presently, all of the goods use microporous polyolefin films. The high-strength microporous polyolefin films also find applications in packaging industries. The polyolefins create a liquid barrier due to their hydrophobic character, whereas the microporosity allows permeation of moist air, thereby providing comfort. The introduction of microporosity in the polyolefin film is rather an art than a science. One of the techniques of generating microporosity is by the pulling of a polyolefin at the interface of a solid inclusion. The other technique includes pulling of pure polyolefin films, which are mainly used for packaging, to create interlamellar voids or pores in the films. This review article discusses the theory of diffusion through the microporous film and the various factors of microporosity such as the addition of filler, its nature (organic or inorganic), size and quantity, film drawing temperature, stretch ratio, its direction (uniaxial and biaxial), and above all, the type of polyolefins used. The aim of this review is to introduce readers to the fascinating science and technology of breathable microporous polyolefin films.