A precursor of an acetylene end-capped polyimide oligomer having the structure: ##STR21## where R has the structure: ##STR22## ##STR23## where X is --CF2 --or a bond; where R' is selected from the group consisting of a phenylene group, a naphthylene group, or ##STR24## where X is as defined above; and where R is an aryl group bearing a substituent having the structure: ##STR25## and where n has a