GB942388A - Process for preparing copolymers - Google Patents

Abstract

Cross-linked copolymer structures exceeding 0.25 inch is at least two dimensions are prepared by a process in which a monomer mixture of polyethylenically unsaturated monomer in which the unsaturated groups are in non-conjugated relationship and monoethylenically unsaturated monomer is polymerized in the presence of a precipitant which is a non-aqueous liquid (a) which acts as a solvent for the monomer mixture and is chemically inert under the polymerization conditions, and (b) which is present in such amount not exceeding 60% by weight of precipitant liquid and monomer mixture and which exerts so little solvating action on the product cross-linked copolymer that phase separation of the product copolymer takes place as evidenced by the fact that the product copolymer is no more than semi-transparent, and preferably opaque, when associated with a fluid having a different refractive index. Many suitable monomers are specified, including monovinyl aromatic hydrocarbons, acrylic, methacrylic and crotonic esters, vinyl heterocyclic nitrogen compounds and dialkyl maleates, fumarates, itaconates and glytaconates; and polyvinyl aromatic hydrocarbons, polyvinyl and polyallyl ethers, ketones and sulphides, allyl esters of unsaturated acids, polyvinyl and polyallyl esters, acrylic and methacrylic esters of polyhydric alcohols, N,N1-alkylene bis acrylamides and 1,2-di (a -methylmethylene sulphonamido) ethylene. Many suitable precipitants are listed including alcohols, esters, nitriles and aliphatic and aromatic hydrocarbons. Polymerization may be effected, preferably under anaerobic conditions, in the presence of free radical initiators, e.g. organic peroxides and hydroperoxides, and azo compounds, or in the presence of ultraviolet light and benzoin or azobisbutyronitrile, between spaced glass plates or in moulds. The results of copolymerizing syrene and divinyl benzene in the presence of various proportions of t. amyl alcohol, sec. butanol and n-butanol are tabulated and examples describe the copolymerization of (I) styrene and divinyl benzene in sec. butanol with benzoyl peroxide; (II) styrene and divinyl benzene in isooctane, n-heptane, acetonitrile, t. amyl alcohol or sec. butanol with benzoyl peroxide; (III) methyl methacrylate and 1,3-butanediol dimethacrylate in isooctane, n-heptane, cyclohexane, 2-ethylhexanol, t. amyl alcohol, sec. butanol or methyl alcohol with benzoyl peroxide; (IV) styrene and divinyl benzene in n-heptane with benzoyl peroxide; (V) methyl methacrylate and divinyl benzene in 2-ethylhexyl acetate with lauroyl peroxide; (VI) styrene and divinyl benzene in isooctane; (VII) methyl acrylate and divinyl benzene or 1,3-butanediol dimethacrylate in isooctane with benzoyl peroxide; (VIII) 2-methyl-5-vinyl pyridine and divinyl benzene in isooctane or n-heptane with benzoyl peroxide; and (IX) n-butyl acrylate and divinyl benzene in isooctane with benzoyl peroxide. The products possess porosity in the form of microscopic channels and may be used for structures having controlled light transmission, flotation devices, catalyst carriers and for potting electrical components.