| Popis: |
A study has been made of some correlations in the chemical cyclization of poly- (amino-acids) by treatment of the latter in solution in N,N-dimethylacetamide with a mixture of acetic anhydride and pyridine, taking the reaction between 3,3',4,4'- benzophenonetetracarboxylic acid dianhydride and 9,9-bis-(4-aminophenyl)fluorene as an example. Various other tertiary amines (pKa=4–11 were used in place of pyridine, in combination with acetic anhydride, for cyclization of poly(amino-acids). Polyimides were prepared by chemical cyclization of poly(amino-acids) in various organic media and it is shown that polyimides of high η1n are formed in solvents in which the poly(amido-acid) dissolves or swell. |
