Process for the preparation of polyimides or of their biodegradable polypeptide hydrolysates
US5688902A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 27, 1996 |
| Grant date | Nov 18, 1997 |
| Priority date | — |
| Expiry date | Jun 27, 2016 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC11D3/3719
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Process for the preparation of polyimides or of their polypeptide hydrolysates which are at least 80% biodegradable, by thermal polycondensation of at least one amino acid, optionally followed by hydrolysis, the thermal polycondensation step being carried out in the presence of at least one "acid catalyst" chosen from PA1 sulphuric, nitric, phosphorous, sulphurous, hydrofluoric, silicic and sulphonic acids, organic sulphonic acids containing less than 50 carbon atoms, amino acids bearing a non-carboxyl strong acid function, organic phosphonic acids, organic carboxylic acids having a pK.sub.a lower than or equal to 5, preferably lower than or equal to 3; PA1 precursors of these acids; PA1 salts of these acids and of an amino acid which is similar to or different from that or those used; PA1 salts of these acids and of a polyimide derived from the polycondensation of at least one amino acid which is similar to or different from that or those used; PA1 hydrochloric acid and its precursors PA1 salts of hydrochloric acid and of an amino acid which is similar to or different from that or those used, when the amino acid to be polycondensed is other than glutamic acid; PA1 salts of hydroch…
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