Synthesis and properties of azobenzene‐containing poly(1‐alkyne)s with different functional pendant groups

Abstract

Abstract1‐Alkynes containing azobenzene mesogenic moieties [HCC(CH2)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(C6H5)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. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4532–4545, 2006

Synthesis and Properties of Light-Emitting Polythiophene Derivatives Bearing Terphenyl Mesogenic Pendant

“…The polythiophene family is well known for its environmental stability, melt and solution processability, and versatile synthesis, which allow us to have a significant control over optical and electronic properties [11]. Conjugated polymers with liquid-crystalline (LC) groups in their side chains are currently drawing interest from the viewpoint of multifunctional electrical and optical materials [12][13][14][15][16][17][18][19][20][21][22][23][24][25]. In side chain type of LC-conjugated polymer, the main chain can be aligned by virtue of spontaneous orientation of the LC side chain.…”

A novel type of optically active helical liquid crystalline polymers: Synthesis and characterization of poly(p‐phenylene)s containing terphenyl mesogen with different terminal groups

“…Attracted by the application perspective, recently, a variety of SCLCCP based on different conjugated main chain have been prepared, such as polyacetylenes, polythiophenes, and polyphenylenes, which can be endowed with such functional properties as mesomorphism, luminescence, photoconductivity, gas permeability, chain helicity 6–19. Tang and coworkers have synthesized a series of polyacetylenes bearing light‐emitting chromophore with different functional bridges and spacer length, such as {[CHC(CmH 2 m + 1 )‐OCO‐biphenyl‐OCO(CH 2 ) 10 CH 3 ]},20 {[ArCC(CH 2 ) m O‐biphenyl‐O(CH 2 ) 6 CH 3 ]}21 and {[ArCC(CH 2 ) m O‐Naphthyl]},22 which found that the light‐emitting chromophore endows the polymer with high luminescence, and the longer spacers favor the strong light emitting as well as better packing arrangement of the mesogens.…”

Polymerization of aliphatic alkynes with heterogeneous Mo catalysts supported on mesoporous molecular sieves

“…Nevertheless, the assignment of this signal to a particular main chain configuration was not unequivocal. For poly(1‐alkyne)s prepared with Rh homogeneous catalysts,25, 37, 38 the 5.9 ppm signal was mostly assigned to the main‐chain olefinic proton on double bonds with cis configuration. This assignment came from the cis ‐transoidal stereoselectivity of Rh‐based catalysts, which was well proved in the case of polymerization of phenylacetylene type monomers 39.…”