| 摘要 |
<p>1,261,484. Polymer blend; vinyl aromatic/ siloxane block copolymers. DOW CORNING CORP. 12 Feb., 1970 [10 March, 1969], No. 6805/70. Headings C3P and C3T. A blend consists of: (A) a vinyl aromatic polymer of the repeating unit formula wherein R<SP>1</SP> is H or methyl.; and G is a monovalent aromatic radical containing 1-3 benzenoid rings which may each have up to 3 aliphatic organic substituents selected from C 1-6 alkyl; cycloalkyl or alkoxy, provided that no substituent which is ortho to the group has more than 1 carbon atom; and (B) a block copolymer of the formula wherein R is a C 1-30 monovalent hydrocarbon; R<SP>11</SP> is a C 1-18 monovalent hydrocarbon; Z is R<SP>11</SP> or a hydroxyl radical; x has an average value of 20-5000; y has an average value of 20-5000; said block copolymer having a molecular weight of 7000-1,000,000, 20-70% by weight being silicon containing units and 30- 80% by weight being units of the organic block; the block copolymer being present as 0À1-20% by weight based on the vinyl aromatic polymer (A), and the monovalent radicals represented by R<SP>1</SP> and G being the same in both (A) and (B). In the examples the block copolymer (B) is prepared by polymerizing styrene with butyllithium in cyclohexane, followed by polymerization of hexamethylcyclotrisiloxane in the presence of the styrene polymer, the resulting product being neutralized with dimethylvinylchlorosilane, to give a dimethylvinylsiloxy terminated polymer, or with acetic acid, to give a silanol terminated polymer. Preferably a proportion of hexamethylcyclotrisiloxane to give at least one trisiloxane unit per polystyrene molecule but not exceeding 40% of the total trisiloxane used is prereacted with the lithium terminated polystyrene. The block copolymer (B) is then added to a solution of commercial polystyrene in toluene, and the solvent evaporated to give a film of the polymer blend. Many other examples are given in. which the organic block is derived from 1-methyl styrene,α-methyl styrene, vinyl naphthalene, 4-propyl styrene, 3-methoxy styrene, 4-phenyl styrene, 3-hexyl-5-methyl styrene, vinyl anthracene, 4-tolyl styrene. or vinyl tetrahydronaphthalene; and the siloxane block is dimethylvinylsiloxy-, dimethylsilanol-, dimethyl phenyl siloxy-, methyl diphenyl siloxy-, dimethyl octadecyl siloxy-, dimethyl (diphenyl) siloxy-, dimethyl tolyl siloxy-, dimethyl #-hydroxyethylsiloxy- and dimethyl hexylsiloxy-terminated poly(dimethylsiloxane).</p> |
