SYNTHESIS AND PROCESSING OF HETEROCYCLIC POLYMERS AS ELECTRONIC, OPTOELECTRONIC, AND NONLINEAR-OPTICAL MATERIALS .4. NEW CONJUGATED RIGID-ROD POLY(BENZOBIS(IMIDAZOLE))S

New conjugated rigid-rod poly(benzobis(imidazole))s incorporating vary ing lengths of trans-polyene segments and 1,4-phenylenebis(vinylene) l inkages have been synthesized and characterized by infrared, H-1 MMR, and electronic absorption spectra. Thin films of the polymers were pre pared from their soluble coordination complexes. The pi-pi optical ba nd gap of thin films of the new polymers was in the range 1.8-2.3 eV w hich is smaller than the corresponding poly(benzobis(thiazole))s. In s pite of the structural modifications which ensure strong interchain in teractions in the new polymers, they still exhibit significant moistur e sensitivity, absorbing equilibrium moisture of similar to 6-9 wt % w hich is however smaller than the well-known poly(1,3-phenylenebibenzim idazole) (PBI) which absorbs similar to 15 wt %. It is suggested that the moisture sensitivity of the poly(benzobis(imidazole))s is intrinsi c to the N-H group and also partly explains the luminescence quenching in thin films. However, the poly(benzobis(imidazole))s are highly flu orescent in dilute solution.