Substituent effect on azobenzene‐based liquid‐crystalline organophosphorus polymers

Abstract

An Erratum has been published for this article in Journal of Polymer Science Part A: Polymer Chemistry (2003) 41(23) 3862A new series of combined‐type, azobenzene‐based organophosphorus liquid‐crystalline polymers were synthesized, and their photoisomerization properties were studied. The prepared polymers contained azobenzene units as both the main‐chain and side‐chain mesogens. Various groups were substituted in the terminal of the side‐chain azobenzene mesogen, and the effects of the substituents were investigated. All the polymers were prepared at the ambient temperature by solution polycondensation with various 4‐substituted phenylazo‐4′‐phenyloxyhexylphosphorodichloridates and 4,4′‐bis(6‐hydroxyhexyloxy) azobenzene. The polymers were characterized with gel permeation chromatography, Fourier transform infrared, and 1H, 13C, and 31P NMR spectroscopy. Thermogravimetric analysis revealed that all the polymers had high char yields. The liquid‐crystalline behavior of the polymers was examined with hot‐stage optical polarizing microscopy, and all the polymers showed liquid‐crystalline properties. The formation of a mesophase was confirmed by differential scanning calorimetry (DSC). The DSC data suggested that mesophase stability was better for electron‐withdrawing substituents than for halogens and unsubstituted ones. Ultraviolet irradiation studies indicated that the time taken for the completion of photoisomerization depended on the dipolar moment, size, and donor–acceptor characteristics of the terminal substituents. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3188–3196, 2003

Liquid crystalline and photoactive poly[4,4′-stilbeneoxy]alkylbiphenylphosphates

“…Phosphorous, being a non-metal overcomes this problem, when incorporated into the polymer [10][11][12]. Our earlier studies in this direction showed that the inclusion of phosphate group into the polymer backbone improved their solubility, thermal stability and char yield and reduced the glass-transition temperature (T g ) [13][14][15][16]. Literature reveals that investigation on the synthesis of photo-crosslinkable liquid crystalline polymers is scarce.…”

Ionic conductivity probed in main chain liquid crystalline azobenzene polyesters

“…The molecular weight reported in literature for main chain azo polymers generally indicates incorporation of 6-8 repeating units. 41,42 In the polymers reported here, the extent of formation of new ester linkage could be estimated based on the integration of the new ester peak at 4.48 ppm (methylene ester) from the corresponding 1 H-NMR spectra. The actual peak integration value and the percentage of new ester linkage is given in the Supporting Information Table S1.…”

Virus-based Photo-Responsive Nanowires Formed By Linking Site-Directed Mutagenesis and Chemical Reaction

“…S4b) in purified and freeze-dried forms were measured. The characteristic peak due to the azo linkage (−N = N−) attached to tyrosine ring is identified at ~1508 cm −1 3334 and methoxy peaks are identified at 1246 and 1036 cm −1 in the methoxy-azo-M13 phage. In the case of nitro-azo-M13 phage, the azo linkage (−N = N−) identified between 1519–1479 cm −1 is found to be coupled with NO 2 stretching.…”