Process for preparation of block copolymers
US4291139A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 9, 1977 |
| Grant date | Sep 22, 1981 |
| Priority date | — |
| Expiry date | Mar 9, 1997 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08F297/044
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The process described herein involves the preparation of block copolymers of the S-B-S type wherein S represents a block of polystyrene and B represents a block of polybutadiene. In order to have the initial polystyrene block soluble in the polymerization medium, cyclohexane and aromatic hydrocarbons have been used as the diluent or solvent in these polymerizations. The present process permits the use of hexane as diluent by first preparing a "foot" or small block of homopolydiene to which the initial polystyrene block is thereafter attached. This small block of homopolydiene represents no more than 12 parts, preferably no more than 10 parts by weight of homopolydiene per 100 parts by weight of the block of polystyrene to which it is attached. Generally therefore this block has a molecular weight of 200-5000 depending on the size of the attached polystyrene block and is not large enough to alter the properties of the resultant S-B-S block copolymer except to give the initial polystyrene block greater dispersibility in hexane, heptane, etc.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.