Effects of methyl substitution of poly(9-alkyl-9H-carbazole-2,7-diyl)s at the 3,6-positions on their physical properties

The preparation and characterization of poly(3,6-dimethyl-9-alkyl-9H-carbazole-2,7-diyl)s P1 and poly(3,6-dimethyl-9-alkyl-9H-carbazole-alt-9-alkyl-9H-carbazole-2,7 -diyl)s alternating copolymers P2 are presented. The polymers were prepared via Suzuki cross-coupling reactions, and two different alkyl substituents were used for both classes of polymers to investigate the effects of their different steric bulks on the properties of the resulting materials. Both classes of materials provided wide-band-gap polymers that emit in the blue part of the electromagnetic spectrum. Cyclic voltammetry studies on the two classes of polymers indicate greater electrolytic stability of these new polymers as compared to poly(9-alkyl-9H-carbazole-2,7-diyl)s as a result of a full or partial methyl functionalization of the 3,6-positions on carbazole repeat units on the polymer chains. The new polymers are also thermally stable up to 350 degrees C.