GB1227250A - - Google Patents

Abstract

1,227,250. Ordered diorganosiloxane block copolymers. FARBENPABRIKEN BAYER A.G. 17 Dec., 1968 [29 Dec., 1967], No. 59875/68. Heading C3T. Diorganosiloxane block copolymers containing segments (of e.g. 3-5 siloxane units) grouped into two or more blocks are prepared by (1) reaction of an anionic polymerization initiator MX, wherein M is K or Na and X is H, OH or an alkyl or aryl radical or a carbanionproducing hydrocarbon or a group wherein each Q is an alkyl, alkenyl or aryl group and Q<SP>1</SP> and Q<SP>11</SP> are each as Q or OM, with a cyclic polysiloxane containing units RR<SP>1</SP>SiO wherein each R is an alkyl, alkenyl, aryl or alkaryl group and each R1 is an alkyl or alkenyl group, then (2) reaction of the product in the presence of a proton-free polar solvent with a hexaorganocyclotrisiloxane having units R<SP>11</SP>R<SP>111</SP>SiO wherein each R<SP>11</SP> and R<SP>111</SP> represents an aryl or alkaryl group; (3) optionally repeating step (2) with a further cyclotrisiloxane having units RR<SP>1</SP>SiO or R<SP>11</SP>R<SP>111</SP>SiO; and (4) neutralizing the product with an acid or a triorganochiorosilane, diorganodichlorosilane, or mono- or di-chloroterminated polydiorganosilane, the step (2) being conducted at 0-60‹ C. when M is K and at 40- 120‹ C. when M is Na. The cyclic siloxane of step (1) is, e.g., a trimer, tetramer or pentamer and may be diluted with a proton-free solvent; the cyclotrisiloxane of step (2) is preferably previously diluted with e.g. benzene, toluene or xylene. In Examples 1-5 Me 3 SiOK or Me 3 SiONa or Me 2 Si(ONa) 2 in tetrahydrofuran is mixed with octamethylcyclotetrasiloxane, alone or mixed with tetramethyltetravinylcyclotetrasiloxane, or with hexamethylcyclotrisiloxane; the product is reacted with hexaphenylcyclotrisiloxane dissolved in benzene, and this product is neutralized with glacial acetic acid; in Example 4 a pyridine/benzene solvnet is used throughout and Me 3 SiCl is used for the neutralization.