Jingye Zhou, Xiaofang Chen, Xinghe Fan
Aug 1, 2006
Citations
0
Influential Citations
17
Citations
Journal
Journal of Polymer Science Part A
Abstract
1-Alkynes containing azobenzene mesogenic moieties [HC=C(CH 2 ) 9 -O-ph-N=N-ph-O-R; R = ethyl (1), octyl (2), decyl (3), (S)-2-methylbutyl (4), or (S)-1-ethoxy-1-oxopropan-2-yl (5); ph = 1,4-phenyl] were synthesized and polymerized in the presence of a Rh catalyst {(nbd)Rh + [B(C 6 H5] 4 ] - ; nbd = 2,5-norbornadiene) to yield a series of liquid-crystalline polymers in high yields (e.g., >75%). These polymers had moderate molecular weights (number-average molecular weight > 12,000), high cis contents in the main chain (up to 83%), good thermal stability, and good solubility in common organic solvents, such as tetrahydrofuran, chloroform, and dichloromethane. These polymers were thoroughly characterized by a combination of infrared, nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, polarized optical microscopy, and two-dimensional wide-angle X-ray diffraction techniques. The liquid-crystalline behavior of these polymers was dependent on the tail group attached to the azobenzene structure. Poly-1, which had the shortest tail group, that is, an ethyl group, showed a smectic A mesophase, whereas poly-2, poly-3, and poly-5, which had longer or chiral tail groups, formed smectic C mesophases, and poly-4, which had another chiral group attached to the azobenzene structure, showed a chiral smectic C mesophase in both the heating and cooling processes.