Polymers, methacrylate

The action of sulphuric acid alone upon acetone cyanohydrin affords a-methylacrylic acid. The methyl methacrylate polymers are the nearest approach to an organic glass so far developed, and are marketed as Perspex (sheet or rod) or Dialcon (powder) in Great Britain and as Plexiglass and Luciie in the U.S.A. They are readily depolymerised to the monomers upon distillation. The constitution of methyl methacrylate polymer has been given as ... 

Place 25 g. of methyl methacrylate polymer (G.B. Diakon (powder). Perspex (sheet) U.S.A. Lucite, Plexiglass) in a 100 ml. Claisen flask, attach an efficient condenser e.g., of the double smface type) and distil with a small luminous flame move the flame to and fro around the sides of the flask. At about 300° the polymer softens and undergoes rapid depolymerisation to the monomer, methyl methacrylate, which distils over into the receiver. Continue the distillation until only a small black residue (3-4 g.) remains. Redistil the hquid it passes over at 100-110°, mainly at 100-102°. The yield of methyl methacrylate (monomer) is 20 g. If the monomer is to be kept for any period, add 0 -1 g. of hydro quinone to act as a stabiUser or inhibitor of polymerisation. 

Another type of synthetic polymer-based chiral stationary phase is formed when chiral catalyst are used to initiate the polymerisation. In the case of poly(methyl methacrylate) polymers, introduced by Okamoto, the chiraUty of the polymer arises from the heUcity of the polymer and not from any inherent chirahty of the individual monomeric subunits (109). Columns of this type (eg, Chiralpak OT) are available from Chiral Technologies, Inc., or J. T. Baker Inc. 

Acrylics. Acetone is converted via the intermediate acetone cyanohydrin to the monomer methyl methacrylate (MMA) [80-62-6]. The MMA is polymerized to poly(methyl methacrylate) (PMMA) to make the familiar clear acryUc sheet. PMMA is also used in mol ding and extmsion powders. Hydrolysis of acetone cyanohydrin gives methacrylic acid (MAA), a monomer which goes direcdy into acryUc latexes, carboxylated styrene—butadiene polymers, or ethylene—MAA ionomers. As part of the methacrylic stmcture, acetone is found in the following major end use products acryUc sheet mol ding resins, impact modifiers and processing aids, acryUc film, ABS and polyester resin modifiers, surface coatings, acryUc lacquers, emulsion polymers, petroleum chemicals, and various copolymers (see METHACRYLIC ACID AND DERIVATIVES METHACRYLIC POLYMERS). 

The most common VI improvers are methacrylate polymers and copolymers, acrylate polymers (see Acrylic ester polymers), olefin polymers and copolymers, and styrene—butadiene copolymers. The degree of VI improvement from these materials is a function of the molecular weight distribution of the polymer. VI improvers are used in engine oils, automatic transmission fluids, multipurpose tractor fluids, hydrautic fluids, and gear lubricants. Their use permits the formulation of products that provide satisfactory lubrication over a much wider temperature range than is possible using mineral oils alone. 

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