A crosslinkable oligomer formed by reacting:(a) 2 moles of a crosslinking phenylimide acid halide of the general formula: ##STR34## wherein D=an unsaturated hydrocarbon radical;i=1 or 2: and ??=phenyl (b) n moles of a diacid halide; and (c) n+1 moles of at least one four-functional compound of the general formula: ##STR35## wherein R is a hydrocarbon radial, Y is selected from the group consisting