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Ethylene Glycol Dimethacrylate
Ethylene glycol dimethylacrylate (EGDMA) is a ester, diester formed by condensation of two equivalents of methacrylic acid and one equivalent of ethylene glycol. EGDMA can be used in free radical copolymer Cross-link, crosslinking reactions. When used with methyl methacrylate, it leads to gel point at relatively low concentrations because of the nearly equivalent reactivities of all the double bonds involved. It is used as a monomer to prepare hydroxyapatite/poly methyl methacrylate composites. EGDMA can be used in free radical copolymer crosslinking reactions. Its toxicity profile has been fairly well studied. It is sometimes called ethylene dimethacrylate. References Monomers Methacrylate esters Glycol esters {{ester-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigma-Aldrich
Sigma-Aldrich (formally MilliporeSigma) is an American chemical, life science, and biotechnology company owned by the multinational chemical conglomerate Merck Group. Sigma-Aldrich was created in 1975 by the merger of Sigma Chemical Company and Aldrich Chemical Company. It grew through various acquisitions until it had over 9,600 employees and was listed on the Fortune 1000. The company has two United States headquarters, in St. Louis and Burlington, MA and has operations in approximately 40 countries. In 2015, the multinational chemical conglomerate Merck Group acquired Sigma-Aldrich for $17 billion. The company is currently a part of Merck's life science business and in combination with Merck's earlier acquired Millipore Corporation, Millipore, operates as MilliporeSigma. It is headquartered in Burlington, Massachusetts, United States. History Sigma Chemical Company of St. Louis and Aldrich Chemical Company of Milwaukee were both American specialty chemical companies when they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ester
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods. Esters can be formed from oxoacids (e.g. esters of acetic acid, carbonic acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condensation
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within the atmosphere. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition. Condensation is usually associated with water. Initiation Condensation is initiated by the formation of atomic/molecular clusters of that species within its gaseous volume—like rain drop or snow flake formation within clouds—or at the contact between such gaseous phase and a liquid or solid surface. In clouds, this can be catalyzed by water-nucleating proteins, produced by atmospheric microbes, which are capable of binding gaseous or liquid water molecules. Reversibility scenarios A few distinct rev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methacrylic Acid
Methacrylic acid, abbreviated MAA, is an organic compound with the formula CH2=C(CH3)CO2H. This colorless, viscous liquid is a carboxylic acid with an acrid unpleasant odor. It is soluble in warm water and miscible with most organic solvents. Methacrylic acid is produced industrially on a large scale as a precursor to its esters, especially methyl methacrylate (MMA), and to poly(methyl methacrylate) (PMMA). Production In the most common route, methacrylic acid is prepared from acetone cyanohydrin, which is converted to methacrylamide sulfate using sulfuric acid. This derivative in turn is hydrolyzed to methacrylic acid, or esterified to methyl methacrylate in one step. Another route to methacrylic acid starts with isobutylene, which obtainable by dehydration of ''tert''-butanol. Isobutylene is oxidized sequentially to methacrolein and then methacrylic acid. Methacrolein for this purpose can also be obtained from formaldehyde and ethylene. Yet a third route involves the dehy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylene Glycol
Ethylene glycol ( IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes: as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odorless, colorless, flammable, viscous liquid. It has a sweet taste but is toxic in high concentrations. This molecule has been observed in outer space. Production Industrial routes Ethylene glycol is produced from ethylene (ethene), via the intermediate ethylene oxide. Ethylene oxide reacts with water to produce ethylene glycol according to the chemical equation : This reaction can be catalyzed by either acids or bases or can occur at neutral pH under elevated temperatures. The highest yields of ethylene glycol occur at acidic or neutral pH with a large excess of water. Under these conditions, ethylene glycol yields of 90% can be achieved. The major byproducts are the oligomers diethylene glycol, triethylene glycol, and tetra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free Radical
A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabolic disorders Metabolism Old age Time in life {{CatAutoTOC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copolymer
In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are sometimes called ''bipolymers''. Those obtained from three and four monomers are called ''terpolymers'' and ''quaterpolymers'', respectively. Copolymers can be characterized by a variety of techniques such as NMR spectroscopy and size-exclusion chromatography to determine the molecular size, weight, properties, and composition of the material. Commercial copolymers include acrylonitrile butadiene styrene (ABS), styrene/butadiene co-polymer (SBR), nitrile rubber, styrene-acrylonitrile, styrene-isoprene-styrene (SIS) and ethylene-vinyl acetate, all of which are formed by chain-growth polymerization. Another production mechanism is step-growth polymerization, which is used to produce the nylon-12/6/66 copolymer of nylon 12, nylon 6 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross-link
In chemistry and biology, a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural polymers (such as proteins). In polymer chemistry "cross-linking" usually refers to the use of cross-links to promote a change in the polymers' physical properties. When "crosslinking" is used in the biological field, it refers to the use of a probe to link proteins together to check for protein–protein interactions, as well as other creative cross-linking methodologies. Although the term is used to refer to the "linking of polymer chains" for both sciences, the extent of crosslinking and specificities of the crosslinking agents vary greatly. Synthetic polymers : 260px, left, Chemical reactions associated with crosslinking of drying oils, the process that produces curing'' refers to the crosslinking of thermosetting">linoleum. Cros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl Methacrylate
Methyl methacrylate (MMA) is an organic compound with the formula . This colorless liquid, the methyl ester of methacrylic acid (MAA), is a monomer produced on a large scale for the production of poly(methyl methacrylate) (PMMA). History MMA was discovered by Bernhard Tollens and his student W. A. Caspary in 1873, who noticed and described its tendency to change into a clear, hard, transparent substance especially in sunlight. Studies on acrylic esters slowly developed until the Staudinger's theory of macromolecules and his research into the nature of polyacrylates allowed control over polymerization. Company Rohm and Haas founded by German chemist Otto Röhm, who investigated the topic for three decades, was finally able to start its industrial production in 1931. Production and properties Given the scale of production, many methods have been developed starting from diverse two- to four-carbon precursors. Two principal routes appear to be commonly practiced. Cyanohydrin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gel Point
In polymer chemistry, the gel point is an abrupt change in the viscosity of a solution containing polymerizable components. At the gel point, a solution undergoes gelation, as reflected in a loss in fluidity. After the monomer/polymer solution has passed the gel point, internal stress builds up in the gel phase, which can lead to volume shrinkage. Gelation is characteristic of polymerizations that include crosslinkers that can form 2- or 3-dimensional networks. For example, the condensation of a dicarboxylic acid and a triol will give rise to a gel whereas the same dicarboxylic acid and a diol will not. The gel is often a small percentage of the mixture, even though it greatly influences the properties of the bulk. Mathematical definition An infinite polymer network appears at the gel point. Assuming that it is possible to measure the extent of reaction, p, defined as the fraction of monomers that appear in cross-links, the gel point can be determined. The critical extent of reac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concentration
In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', '' number concentration'', and '' volume concentration''. The concentration can refer to any kind of chemical mixture, but most frequently refers to solutes and solvents in solutions. The molar (amount) concentration has variants, such as normal concentration and osmotic concentration. Dilution is reduction of concentration, e.g. by adding solvent to a solution. The verb to concentrate means to increase concentration, the opposite of dilute. Etymology ''Concentration-'', ''concentratio'', action or an act of coming together at a single place, bringing to a common center, was used in post-classical Latin in 1550 or earlier, similar terms attested in Italian (1589), Spanish (1589), English (1606), French (1632). Qualitative description Often in informal, non- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Bond
In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist between two different elements: for example, in a carbonyl group between a carbon atom and an oxygen atom. Other common double bonds are found in azo compounds (N=N), imines (C=N), and sulfoxides (S=O). In a skeletal formula, a double bond is drawn as two parallel lines (=) between the two connected atoms; typographically, the equals sign is used for this. Double bonds were introduced in chemical notation by Russian chemist Alexander Butlerov. Double bonds involving carbon are stronger and shorter than single bonds. The bond order is two. Double bonds are also electron-rich, which makes them potentially more reactive in the presence of a strong electron acceptor (as in addition reactions of the halogens). File:Ethene structural.svg, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
