Chain-extending Schiff base terminated polyimides and method of preparation
OwnerGaetano Francis D'Alelioinventor
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Abstract
Aromatic polyimides with Schiff base end groups are chain-extended (molecular weight increase) by heating the polyimides, preferably in the presence of Lewis acid salts as catalyst. Molecular weights are increased with little or no by-product formation. The polyimides can be shaped and formed prior to the polymerization. The aromatic polyimides appropriate for chain-extending are formed by the reaction of aromatic dianhydrides, aromatic diamines and a Schiff base monoamine such as p-amino-benzylidene-aniline, p-amino-benzylidene-4-vinylaniline and p-aminobenzylidine-4-ethynylaniline.
Claims14
A polymeric chain-extending process comprising:
- heating a polyimide, at a temperature in the range of about 150.degree.-450.degree. C, of the formula:
- ##STR9## wherein Ar' is a tetravalent aromatic organic radical, the four carbonyl groups being attached directly to separate carbon atoms and each pair of carbonyl groups being attached to adjacent carbon atoms in the Ar' radical,
- Ar is a divalent aromatic organic radical,
- R is a hydrocarbon radical of 1 to 12 carbon atoms, and
- R" is a hydrocarbon radical of 1 to 12 carbon atoms, and
- n is a positive integer of at least one.
A polymeric chain-extending process comprising:
- heating a polyimide at a temperature in the range of about 150.degree.-450.degree. C. in the presence of about 0.15-3% by weight, based on the weight of the polyimide, of a Lewis acid salt catalyst, said polyimide of the formula:
- ##STR13## wherein Ar' is a tetravalent aromatic organic radical, the four carbonyl groups being attached directly to separate carbon atoms and each pair of carbonyl groups being attached to adjacent carbon atoms in the Ar' radical,
- Ar is a divalent aromatic organic radical, ##STR14## n is a positive integer from 1 to 20.
Dependencies are inferred from the claim text.