Method for preparation of very high molecular weight polycarborane siloxanes
US5208310A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 16, 1991 |
| Grant date | May 4, 1993 |
| Priority date | — |
| Expiry date | Dec 16, 2011 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G77/56
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
An improved method for the preparation of very high molecular weight polycarborane siloxane polymers in which each of the reactants is first provided in an ultra-pure state by a series of recrystallization procedures in specific solvents. The reactants are then reacted in the following series of steps by: PA0 (a) providing ultra-pure carborane bisdimethyl silanol in dried chlorobenzene solvent, to form a slurry and cooling said slurry to -10.degree..+-.5.degree. C.; PA0 (b) adding to said slurry a mixture of ultra-pure dimethylbisureido silane and ultra-pure methylphenylbisureido silane to form a reaction mixture at -10.degree..+-.5.degree. C.; PA0 (c) separating from said reaction mixture a silanol end-capped prepolymer of said polycarborane siloxane polymer; PA0 (d) dissolving said prepolymer in chlorobenzene to form a solution; and PA0 (e) adding to said prepolymer solution an excess of said ultra-pure bisureido silane selected from the group consisting of dimethylbisureido silane, methylphenylbisureido silane and a mixture thereof, to form said very high molecular weight polycarborane siloxane polymer. Alternatively, step (e) may be performed at 60.degree.-70.degree. C. to furt…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.