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Polymers Of Intrinsic Microporosity
Polymers of intrinsic microporosity (PIMs) are a unique class of microporous material developed by research efforts led by Neil McKeown, Peter Budd, et al. PIMs contain a continuous network of interconnected intermolecular voids less than 2 nm in width. Classified as a porous organic polymer, PIMs generate porosity from their rigid and contorted macromolecular chains that do not efficiently pack in the solid state. PIMs are composed of a fused ring sequences interrupted by Spiro-centers or other sites of contortion along the backbone. Due to their fused ring structure PIMs cannot rotate freely along the polymer backbone, ensuring the macromolecular components conformation cannot rearrange and ensuring the highly contorted shape is fixed during synthesis. Synthesis PIMs require that the non-network macromolecular structure is rigid and non-linear. In order to maintain permanent microporosity the rotation along the polymer chain must be prohibited through the use of fused ring st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microporous Material
A microporous material is a material containing pores with diameters less than 2 nm. Examples of microporous materials include zeolites and metal-organic frameworks. Porous materials are classified into several kinds by their size. The recommendations of a panel convened by the International Union of Pure and Applied Chemistry (IUPAC) are: See page 1745. *Microporous materials have pore diameters of less than 2 nm. *Mesoporous materials have pore diameters between 2 nm and 50 nm. *Macroporous materials have pore diameters of greater than 50 nm. Micropores may be defined differently in other contexts. For example, in the context of porous aggregations such as soil, micropores are defined as cavities with sizes less than 30 μm. Uses in laboratories Microporous materials are often used in laboratory environments to facilitate contaminant-free exchange of gases. Mold spores, bacteria, and other airborne contaminants will become trapped, while gases are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neil McKeown
Neil Bruce McKeown FRSE is a chemist who is currently Crawford Professor of Chemistry at the University of Edinburgh. Education He was educated at the University of East Anglia (BSc, 1984; PhD, 1987). Honours McKeown was awarded the Beilby Medal and Prize in 2008, and was elected a Fellow of the Royal Society of Edinburgh in 2017. He was awarded the Tilden Prize The Tilden Prize is an award that is made by the Royal Society of Chemistry for advances in chemistry. The award was established in 1939 and commemorates Sir William A. Tilden, a prominent British chemist. The prize runs annually with up to three ... in 2017. References Year of birth missing (living people) Living people Alumni of the University of East Anglia Academics of the University of Manchester Academics of Cardiff University Academics of the University of Edinburgh {{chemist-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Budd
Peter Martin Budd is a British chemist and a Professor in the Department of Chemistry at The University of Manchester. His research in general is based on polymer chemistry, energy and industrial separations, specifically on the areas of Polymers of intrinsic microporosity (PIMs), energy storage, polyelectrolytes and separation membranes. Education Budd was educated at St Mary's Primary School Finchley (1963 - 1968), M.E.G.M. English School, Asmara (1968 - 1972) and St Lawrence College, Ramsgate (1972 - 1975). He then completed both his Bachelor of Science and Doctor of Philosophy degree at University of Manchester in 1978 and 1981 respectively. His PhD on ''The Synthesis and Properties of Polypeptides'' was supervised by Dr. Colin Price. Research and career Upon completing his PhD, Budd joined the British Petroleum Research Center in Sunbury-on-Thames where he worked on polymers and structural materials as a research chemist for 8 years. In 1989, he joined the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spiro Compound
In organic chemistry, spiro compounds are compounds that have at least two molecular rings with only one common atom. The simplest spiro compounds are bicyclic (having just two rings), or have a bicyclic portion as part of the larger ring system, in either case with the two rings connected through the defining single common atom. The one common atom connecting the participating rings distinguishes spiro compounds from other bicyclics: from ''isolated ring compounds'' like biphenyl that have no connecting atoms, from ''fused ring compounds'' like decalin having two rings linked by two adjacent atoms, and from ''bridged ring compounds'' like norbornane with two rings linked by two non-adjacent atoms.For all four categories, see The specific chapters can be found aan respectively, same access date. For the description featuring adjacent atoms for all but the isolated category, see Clayden, op. cit. Spiro compounds may be fully carbocyclic (all carbon) or heterocyclic (havi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleophilic Substitution
In chemistry, a nucleophilic substitution is a class of chemical reactions in which an electron-rich chemical species (known as a nucleophile) replaces a functional group within another electron-deficient molecule (known as the electrophile). The molecule that contains the electrophile and the leaving functional group is called the substrate. The most general form of the reaction may be given as the following: :\text\mathbf + \ce + \text\mathbf The electron pair (:) from the nucleophile (Nuc) attacks the substrate () and bonds with it. Simultaneously, the leaving group (LG) departs with an electron pair. The principal product in this case is . The nucleophile may be electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged. An example of nucleophilic substitution is the hydrolysis of an alkyl bromide, R-Br under basic conditions, where the attacking nucleophile is hydroxyl () and the leaving group is bromide (). :R-Br + OH- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dibenzodioxin
Dibenzo-1,4-dioxin, also dibenzodioxin or dibenzo-''p''-dioxin (dibenzo-''para''-dioxin), is a polycyclic heterocyclic organic compound in which two benzene rings are connected by a 1,4-dioxin ring. Its molecular formula is C12H8O2. The two oxygen atoms occupy opposite ( ''para''-) positions in the six-membered dioxin ring. Dibenzodioxin is the carbon skeleton of the poisonous polychlorinated dibenzodioxins (PCDDs), often called dioxins. The most harmful PCDD is 2,3,7,8-tetrachlorodibenzodioxin (TCDD). Dioxins and dioxin-like compounds is a category of pollutants that includes PCDDs and other compounds that have similar structure, toxicity, and persistence. Dibenzodioxin is also the skeleton of the polybrominated dibenzodioxins. Isomer The general name dibenzodioxin usually refers to dibenzo-''p''-dioxin. The isomeric compound dibenzo-''o''-dioxin (dibenzo-''ortho''-dioxin) or dibenzo-1,2-dioxin, like the unstable 1,2-dioxin, has two adjacent oxygen atoms ( ''ortho''-). No det ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tröger's Base
Tröger's base is a white solid tetracyclic organic compound. structure and formula of (CH3C6H3NCH2)2CH2. Tröger's base and its analogs are soluble in various organic solvents and strong acidic aqueous solutions due to their protonation. History Tröger's original research in 1887 failed to elaborate the exact structure of his new product that lead Johannes Wislicenus, the departmental director of the time, to assign a mediocre grade for Tröger's thesis. Despite various possible structures had been drawn for Tröger's product, its correct structure remained as a mystery for 48 years, until the final elucidation in 1935 by Spielman. Structure and chirality The nitrogen inversion normally leads to a rapid equilibrium between the enantiomers of chiral amines, that prevents them showing any optical activity. The inversion can be stopped by conformational strain as Tröger's base has demonstrated that nitrogen is capable of forming a stereogenic center in organic molecules. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Separation
Gas separation can refer to any of a number of techniques used to separate gases, either to give multiple products or to purify a single product. Swing adsorption techniques Pressure swing adsorption Pressure swing adsorption (PSA) pressurizes and depressurizes gas around an adsorbent media to selectively adsorb certain components of a gas, allowing others to be selectively discarded. Vacuum swing adsorption Vacuum swing adsorption (VSA) uses the same principle as PSA but swings between vacuum pressures and atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 7 .... The two techniques may be combined and are called "vacuum pressure swing adsorption" (VPSA) in this case. Temperature swing adsorption Temperature swing adsorption (TSA) uses a similar technique to ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Capture And Storage
Carbon capture and storage (CCS) or carbon capture and sequestration is the process of capturing carbon dioxide (CO2) before it enters the atmosphere, transporting it, and storing it (carbon sequestration) for centuries or millennia. Usually the CO2 is captured from large point sources, such as a chemical plant or biomass power plant, and then stored in an underground geological formation. The aim is to prevent the release of CO2 from heavy industry with the intent of mitigating the effects of climate change. CO2 has been injected into geological formations for several decades for enhanced oil recovery and after separation from natural gas, but this has been criticised for producing more emissions when the gas or oil is burned. Carbon capture and utilization (CCU) and CCS are sometimes discussed collectively as carbon capture, utilization, and sequestration (CCUS). This is because CCS is a relatively expensive process yielding a product which is often too cheap. Hence, car ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Gas Separation
Gas mixtures can be effectively separated by synthetic membranes made from polymers such as polyamide or cellulose acetate, or from ceramic materials. While polymeric membranes are economical and technologically useful, they are bounded by their performance, known as the Robeson limit (permeability must be sacrificed for selectivity and vice versa). This limit affects polymeric membrane use for CO2 separation from flue gas streams, since mass transport becomes limiting and CO2 separation becomes very expensive due to low permeabilities. Membrane materials have expanded into the realm of silica, zeolites, metal-organic frameworks, and perovskites due to their strong thermal and chemical resistance as well as high tunability (ability to be modified and functionalized), leading to increased permeability and selectivity. Membranes can be used for separating gas mixtures where they act as a permeable barrier through which different compounds move across at different rates or not move ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permeation
In physics and engineering, permeation (also called imbuing) is the penetration of a permeate (a fluid such as a liquid, gas, or vapor) through a solid. It is directly related to the concentration gradient of the permeate, a material's intrinsic permeability, and the materials' mass diffusivity. Permeation is modeled by equations such as Fick's laws of diffusion, and can be measured using tools such as a minipermeameter. Description The process of permeation involves the diffusion of molecules, called the permeant, through a membrane or interface. Permeation works through diffusion; the permeant will move from high concentration to low concentration across the interface. A material can be semipermeable, with the presence of a semipermeable membrane. Only molecules or ions with certain properties will be able to diffuse across such a membrane. This is a very important mechanism in biology where fluids inside a blood vessel need to be regulated and controlled. Permeation can occ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mixed Matrix Membrane
Mixed is the past tense of ''mix''. Mixed may refer to: * Mixed (United Kingdom ethnicity category), an ethnicity category that has been used by the United Kingdom's Office for National Statistics since the 1991 Census * ''Mixed'' (album), a compilation album of two avant-garde jazz sessions featuring performances by the Cecil Taylor Unit and the Roswell Rudd Sextet See also * Mix (other) * Mixed breed A mixed breed is a domesticated animal descended from multiple breeds of the same species, often breeding without any human intervention, recordkeeping, or selective breeding. Examples include: * Mixed-breed dog, a dog whose ancestry is compl ..., an animal whose parents are from different breeds or species * Mixed ethnicity, a person who is of multiple races * * {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
