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The first example of an artificial molecular machine (a switchable molecular shuttle). The positively charged ring (blue) is initially positioned over the benzidine unit (green), but shifts to the biphenol unit (red) when the benzidine gets protonated (purple) as a result of electrochemical oxidation or lowering of the pH. [10]
Phenol-formaldehyde resins, as a group, are formed by a step-growth polymerization reaction that can be either acid- or base-catalysed.Since formaldehyde exists predominantly in solution as a dynamic equilibrium of methylene glycol oligomers, the concentration of the reactive form of formaldehyde depends on temperature and pH.
Bakelite was produced for the first time in 1872 by Adolf von Baeyer, though its use as a commercial product was not considered at the time. [6]Leo Baekeland was already wealthy due to his invention of Velox photographic paper when he began to investigate the reactions of phenol and formaldehyde in his home laboratory.
Carbon black from vegetable origin is used as a food coloring, known in Europe as additive E153. It is approved for use as additive 153 (Carbon blacks or Vegetable carbon) in Australia and New Zealand [7] but has been banned in the US. [8] The color pigment carbon black has been widely used for many years in food and beverage packaging.
Raw lacquer has a water content of around 25% and appears in a light brown colour. This comes in a standard grade made from Chinese lacquer, which is generally used for ground layers by mixing with a powder, and a high-quality grade made from Japanese lacquer called kijomi-urushi (生正味漆) which is used for the last finishing layers.
Polyethylene glycol (PEG; / ˌ p ɒ l i ˈ ɛ θ əl ˌ iː n ˈ ɡ l aɪ ˌ k ɒ l,-ˈ ɛ θ ɪ l-,-ˌ k ɔː l /) is a polyether compound derived from petroleum with many applications, from industrial manufacturing to medicine.
The Environmental Protection Agency said Tuesday it has finalized a ban on consumer uses of methylene chloride, a chemical that is widely used as a paint stripper but is known to cause liver ...
These coatings are known as silicate mineral paint. An example of the reaction of sodium silicate with the calcium hydroxide found in concrete to form calcium silicate hydrate (CSH) gel, the main product in hydrated Portland cement, follows. [30] Na 2 SiO 3 + y H 2 O + x Ca(OH) 2 → x CaO.SiO 2.y H 2 O + 2NaOH