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AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsPaul M. Hergenrother, Joseph G. Smith, Jr.
Estimating the term…
Controlled molecular weight phenylethynyl terminated imide oligomers (PETIs) have been prepared by the cyclodehydration of precursor phenylethynyl terminated amic acid oligomers. Amino terminated amic acid oligomers are prepared from the reaction of dianhydride(s) with an excess of diamine(s) and subsequently endcapped with phenylethynyl phthalic anhydride(s) (PEPA). The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide under nitrogen at room temperature. The amic acid oligomers are subsequently cyclodehydrated either thermally or chemically to the corresponding imide oligomers. Direct preparation of PETIs from the reaction of dianhydride(s) with an excess of diamine(s) and endcapped with phenylethynyl phthalic anhydride(s) has been performed in m-cresol. Phenylethynyl phthalic anhydrides are synthesized by the palladium catalyzed reaction of phenylacetylene with bromo substituted phthalic anhydrides in triethylamine. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.
A controlled molecular weight imide oligomer terminated with phenylethynyl phthalimide consisting of repeat units having the general structural formula ##STR47## wherein Ar' is a radical selected from the group consisting of ##STR48## wherein the catenation is selected from the group consisting of 2,2';2,3';2,4';
A phenylethynyl terminated amic acid oligomer having the general structural formula:
A process for synthesizing controlled molecular weight imide oligomers terminated with phenylethynyl phthalimide and having the general structural formula ##STR85## which process comprises cyclodehydrating precursor amic acid oligomers terminated with phenylethynyl phthalamic acid and having the general structural formula ##STR86## wherein the cyclodehydrating reaction is carried out in a polar aprotic solvent such as N,N-dimethylacetamide, N-methyl-2-pyrrolidinone, N-cyclohexyl-2-pyrrolidinone, m-cresol, and dimethylsulfoxide;
Dependencies are inferred from the claim text.