GB1138793A - Polymerisation of beta-lactones - Google Patents

Abstract

1,138,793. Polymerizing beta - lactones. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 22 Sept., 1967, No. 43303/67. Heading C3R. Polyesters are made by polymerizing (preferably at 0‹ to 150‹ C.) one or more beta-lactones, at least 50 mole per cent being pivalactone, in a liquid hydrocarbon diluent having a boiling point of below 300‹ C. and in the presence of a solid carboxylate anion-containing initiator at least 80% by weight of which has a particle size of not more than 200 microns but larger than 5 microns. The initiator is substantially insoluble in the diluent, is free from active hydrogen atoms and is either (a) a preformed betaine having a molecular weight below 30,000 and in which the cation may be, e.g. ammonium, pyridinium, morpholinium, phosphonium, arsonium, stibonium or sulphonium, or (b) a " living " prepolymer having a molecular weight of 200 to 30,000 and which has been obtained by reacting a beta-lactone with a nucleophilic agent in a molar ratio of between 20 : 1 and 1 : 40, suitable initiators being phosphines, stibines, arsines, amines, sulphides, sulphoxides, an alkali metal salt, an alkali metal phenolate, thiophenolate, alcoholate or mercaptide, an alkali metal alkyl or aryl, a quaternary phosphonium, stibonium, arsonium, ammonium salt or a tertiary sulphonium compound. Preferably the " living " prepolymers are prepared in an inert fluid diluent and in the presence of a surface-active substance having a hydrocarbon chain with a molecular weight of at least 200 and having one or more hydroxyl, amino, carbonamido or imido groups.