Synthesis and characterization of side-chain liquid-crystalline polyacrylates containing azobenzene moieties

• Main Authors: Silong, S., Lutfor, M.R., Ab Rahman, M.Z., Wan Yunus, W.M.Z.
• Format: Article
• Language: English
• Published: 2002
• Online Access: http://psasir.upm.edu.my/id/eprint/114744/1/114744.pdf; http://psasir.upm.edu.my/id/eprint/114744/; https://onlinelibrary.wiley.com/doi/10.1002/app.11123

Syntheses of novel liquid-crystalline polymers containing azobenzene moieties were performed by a convenient route with an acrylate backbone. The azobenzenes were key intermediates of the monomers, and side-chain liquid-crystalline polymers were prepared, that is, poly[α-(4-[(4-acetylphenyl)azo]phenoxy)alkyloxy]acrylates, for which the spacer length was 3 or 11 methylene units. In addition, poly[3(4-[(3,5-dimethylphenyl)azo]phenoxy)propyloxy]acrylate was prepared with a spacer length of 3 methylene units. The structures of the precursors, monomers, and polymers were characterized with Fourier transform infrared, 1H-NMR, and 13C-NMR techniques. The polymers were obtained by conventional free-radical polymerization with 2,2′-azobis-isobutyronitrile as an initiator. The phase-transition temperatures of the polymers were studied with differential scanning calorimetry, and the phase structures were evaluated with a polarizing optical microscopy technique. The results showed that two of the monomers and their corresponding polymers exhibited nematic liquid-crystalline behavior, and one of the monomers and its corresponding polymer showed smectic liquid-crystalline behavior. © 2002 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 86.