Patent GB-857145-A (GB)
Title: Block copolymers
Inventor: TWIGG GEORGE HILTON
IPC: C08F293/00
Filed: 1957-03-22
Abstract: Block copolymers are made by mixing monomeric material capable of undergoing addition polymerization with a polymerization initiator having two initiating centres of different reactivities, causing one of the centres to initiate polymerization under conditions which do not activate the second initiating centre, separating polymeric material containing chemically bound active residues of initiator from excess initiator and monomeric material, mixing the polymeric material with a different monomeric material and causing polymerization of the latter under the influence of the second initiating centre. Polymerization initiators specified are those of the formulae:  <FORM:0857145/IV(a)/1> and corresponding o and p isomers and their homologues; <FORM:0857145/IV(a)/2> and its m and o isomers and their homologues:  <FORM:0857145/IV(a)/3> where at least one of the R1 groups has the formula <FORM:0857145/IV(a)/4> and the other R1 group has the formula:  <FORM:0857145/IV(a)/5> or is hydrogen, and the R groups represent lower alkyl groups which may be the same or different; the methyl ester of p - 2 - propyl - 2 - hydroperoxy perbenzoic acid, and compounds containing an azo group and a peroxide or hydroperoxide group. The preferred initiator is bis (m - 2 - hydroperoxy - 2 - propyl - alphacumyl) peroxide.  When the initiator contains a hydroperoxide group the first polymerization step may be carried out under redox conditions employing a compound of a multivalent metal, e.g. iron, copper and cerium salts and osmic acid, and, when using an aqueous emulsion polymerization technique, water soluble reducing agents such as sugars.  Alternatively, when the temperature of activation of the two initiating centres is different the two polymerization stages may be carried out at different temperatures.  The polymerization reaction in either the first or the second stage may be carried out in bulk, solution or aqueous emulsion or suspension.  Monomers specified are those containing olefinic unsaturation, e.g. styrene and methyl methacrylate.ALSO:The invention comprises peroxides of the formula : <FORM:0857145/IV(b)/1> where at least one of the R1 groups has the formula :  <FORM:0857145/IV(b)/2> and the other R1 group has the formula :  <FORM:0857145/IV(b)/3> or is hydrogen and the R groups represent lower alkyl groups which may be the same or different.  The examples describe the preparation of bis (m-2-hydroperoxy-2-propyl-alphaamyl) peroxide (1) by reacting bis (m-2-hydroperoxy-2-propyl) benzene and m-(2-hydroxy-2-propyl) alpha: alpha-dimethyl benzyl hydroperoxide whilst dissolved in a mixture of diethyl ether and acetic acid and in the presence of perchloric acid ; (2) by reacting m-bis-(2-hydroxy-2-propyl) benzene and m (2-hydroxy-2-propyl) alpha: alpha-dimethyl benzyl hydroperoxide in solution in glacial acetic acid and in the presence of perchloric acid to obtain bis (m-2-hydroxy-2-propyl-alpha-cumyl) peroxide which is then treated with hydrogen peroxide to obtain the desired product ; and (3) by reacting m-(2-hydroperoxy-2-propyl) isopropyl benzene with m-(2-hydroxy-2-propyl) isopropyl benzene under the conditions described in (2) to obtain bis (m-isopropyl alpha-amyl) peroxide which is treated with oxygen followed by extraction with caustic soda, which yields a product which is suspended in water and treated with carbon dioxide to provide the desired product.