Study of Supramolecular Side-Chain and Cross-Linking Polymers by Complexation of Various H-Donor Acids with H-Acceptor Copolymers Containing Pendent Carbazole and Fluorescent Pyridyl Units

Abstract

Two H-bonded acceptor (H-acceptor) homopolymers 14 and 17 were successfully prepared by polymerization of fluorescent pyridyl monomers PBT and PBOT (12 and 13), which were synthesized via Sonogashira coupling and Wittig-Horner reactions. To increase the glass transition temperatures as well as reduce the pi-pi stacking of the photoluminescent (PL) H-acceptor copolymers and their H-bonded polymer complexes, fluorescent monomers 12 and 13 were copolymerized with N-vinylearbazole monomer CAZ (23) to produce H-acceptor copolymers 15-16 and 18-19. Supramolecular side-chain and crosslinking polymers (i.e., H-bonded polymer complexes) obtained by complexation of light-emitting H-acceptor polymers 14-19 with various proton donor (H-donor) acids 20-22 were further characterized by DSC, POM, FTIR, XRD, and PL measurements. The mesomorphic properties can be tuned from the nematic phase in H-acceptor homopolymers (14 and 17) to the tilted smectic C phase in their H-bonded polymer complexes (14/20-21 and 17/20-22) by the introduction of H-donor acids (20-22). Moreover, the PL properties of light-emitting H-acceptor polymers can be adjusted not only by the central structures of the conjugated pyridyl cores but also by their surrounding nonfluorescent H-donor acids. In general, redder shifts of PL emissions in H-bonded polymer complexes occurred when the light-emitting H-acceptor polymers were complexed with H-donors having smaller pKa values. (c) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2734-2753, 2009