Lightly crosslinked polyimides

A crosslinkable polyimide oligomer having the general formula:

• ##STR40## wherein E is the residue of an amine end cap selected from the group consisting of:
• ##STR41## wherein X is selected from the group consisting of:
• ##STR42## A is the residue of a dianhydride selected from the group consisting of, ##STR43## wherein M=--SO.sub.2 --, --S--, --O--, --(CH.sub.3).sub.2 C--, CO or --(CF.sub.3).sub.2 C--, and
• B is the residue of a diamine;
• n=1 or 2;
• R.sub.1 =lower alkyl, lower alkoxy, aryl, substituted aryl, substituted alkyl, aryloxy, or halogen;
• j=0, 1, or 2;
• Me=methyl;
• G=--SO.sub.2 --, --CH.sub.2 --, --S--, or --O--;
• and
• E=methallyl or allyl.

A process for making thermoplastic, solvent-resistant, polyimide oligomers suitable for advanced composites, comprising the step of reacting substantially stoichiometric amounts of a crosslinkable monoanhydride, a diamine, and a dianhydride under an inert atmosphere, wherein the monoanhydride is selected from the group consisting of:

• ##STR45## R.sub.1 =lower alkyl, lower alkoxy, aryl, substituted aryl, substituted alkyl, aryloxy, or halogen;
• j=0, 1, or 2;
• Me=methyl;
• G=--SO.sub.2 --, --CH.sub.2 --, --S--, or --O--;
• and
• E=methallyl or allyl;
• wherein the diamine has:
• terminal amino (--NH.sub.2) groups, a plurality of aromatic radicals, and alternating ether and sulfone linkages connecting the aromatic radicals, wherein each sulfone linkage is selected from the group consisting of:
• --SO.sub.2 --, --S--, --CO--, --(CF.sub.3).sub.2 C--;
• wherein the dianhydride selected from the group consisting of, ##STR46## wherein M=--SO.sub.2 --, --S--, --O--, --(CH.sub.3).sub.2 C--, CO or --(CF.sub.3).sub.2 C--, and
• wherein the oligomer has an average formula weight in excess of about 5000.

A method for making a difunctional, crosslinkable, polyimide oligomer, comprising the step of condensing a difunctional end cap amine of the general formula:

• ##STR47## R.sub.1 =lower alkyl, lower alkoxy, aryl, substituted aryl, substituted alkyl, aryloxy, or halogen;
• j=0, 1, or 2;
• Me=methyl;
• G=--SO.sub.2 --, --CH.sub.2 --, --S--, or --O--;
• and
• E=methallyl or allyl,
• with substantially stoichiometric amounts of a dianhydride selected from the group consisting of, ##STR48## wherein M=--SO.sub.2 --, --S--, --O--, --(CH.sub.3).sub.2 C--, CO or --(CF.sub.3).sub.2 C--, and a diamine under an inert atmosphere.

A method of making a multidimensional, crosslinking, polyimide oligomer, comprising the steps of:

• (a) condensing an etheramine intermediate of the general formula:
• ##STR49## with a dianhydride selected from the group consisting of, ##STR50## wherein M=--SO.sub.2 --, --S--, --O--, --(CH.sub.3).sub.2 C--, CO or --(CF.sub.3).sub.2 C--, and
• to form a multidimensional anhydride;
• and
• (b) adding a diamine and a crosslinkable monoanhydride to the multidimensional anhydride under an inert atmosphere.

A method of making a multidimensional, crosslinking, polyimide oligomer comprising the steps of:

• (a) condensing an etheranhydride intermediate of the general formula:
• ##STR51## with a diamine to form a multidimensional amine;
• and (b) adding a dianhydride selected from the group consisting of, ##STR52## wherein M=--SO.sub.2 --, --S--, --O--, --(CH.sub.3).sub.2 C--, CO or --(CF.sub.3).sub.2 C--, and
• crosslinkable amine end cap to the multidimensional amine under an inert atmosphere.