Allyl Monomers and Polymers

Abstract

AbstractAllyl compounds comprise a large group of ethylenic compounds having unique reactivities and uses often contrasting with those of typical vinyl‐type compounds. Unlike monovinyl compounds, monoallyl compounds do not form homopolymers of high molecular weight by free‐radical or conventional ionic mechanisms. In contrast, many allyl compounds containing two or more reactive double bonds yield solid, high molecular weight polymers by initiation with suitable free‐radical catalysts. A number of polyfunctional allyl esters have achieved importance in polymerization and copolymerization, especially to obtain heat‐resistant cast sheets and thermoset moldings. Diallyl diglycol carbonate or diethylene glycol bis(allyl carbonate) (DADC) was developed to produce by bulk polymerization cast sheets, lenses, and other shapes of outstanding scratch resistance and optical and mechanical properties. Reaction of allyl alcohol in the presence of alkali with diethylene glycol bis(chloroformate) gives the DADC monomer, a colorless liquid of mild odor. The latter is low in toxicity, but can produce skin irritation. DADC is soluble in common organic solvents and in methyl methacrylate, styrene, and vinyl acetate. It is partially soluble in amyl alcohol, gasoline, and ligroin. It is insoluble in ethylene glycol, glycerol, and water. Usage of DADC polymers in impact‐resistant, lightweight eyewear lenses has grown rapidly and is now the principal application. The three isomeric diallyl phthalates are colorless liquids of mild odor, low volatility, and relatively slow polymerization in the early stages. At ca 25% conversion, the viscous liquid undergoes gelation and polymerization accelerates. Diallyl isophthalate (DAIP) polymerizes faster than DAP. Besides application as heat‐resistant molding powders for electronic and other applications, DAIP copolymers have been proposed for optical applications. The largest use of diallyl phthalate thermoset polymers is in moldings and coatings for electronic devices requiring high reliability under long‐term adverse environmental conditions. Monomers such as allyl methacrylate (AMA) and diallyl maleate (DAM) have applications as cross‐linking and branching agents selected especially for the different reactivities of their double bonds. DAM and DAF have pungent odors and are skin irritants. Allyl methacrylate (AMA) is used as cross‐linking agent with methacrylate esters in contact lenses. Triallyl cyanurate (TAC), 2,4,6‐tris(allyloxy)‐s‐triazine, and its isomer triallyl isocyanurate (TAIC) are used as cross‐linking agents with comonomers and for aftercuring preformed polymers such as olefin copolymers in electrical insulations.N,N‐Diallyldimethyl(DADM)ammonium salts are used for the preparation of polyelectrolytes. Copolymers of diallyldimethylammonium chloride with acrylamide have been used in electroconductive coatings.