Synthesis and Characterization of a Series of Azobenzene-Containing Side-Chain Liquid Crystalline Polymers

Abstract

A series of poly{4′-{(X-methacryloyloxyalkylene)methylamino}-4-nitroazobenzene} (pXMAN, where X is the number of methylene units and varies from 2 to 12) polymers with liquid crystalline (LC) properties was synthesized. When annealed above their T g values, the whole series of polymers exhibits a stable smectic A mesophase while only the material with the shorter spacer, p2MAN, presents a smectic phase followed by a nematic phase. The spacing of the smectic layers was determined by X-ray diffraction, revealing intermolecular reorganization by interdigitation of the side-chain mesogens since the smectic layer spacing was larger than a fully extended side chain but less than two extended chains. This behavior is confirmed by temperature dependent aggregation as observed by UV-visible spectroscopy during the transition from an amorphous state to a liquid crystalline phase. The stability of the mesophase is enhanced by intermolecular interactions as argued by enthalpic and thermochromic considerations. Systematic photoinduced birefringence measurements on the various states reveal that the maximum and remnant levels of birefringence decrease with increasing the spacer length and with decreasing the glass transition temperature of the considered liquid crystalline polymer.

Synthesis and Characterization of Novel Amphiphilic Azo-Polymers Bearing Well-Defined Oligo(Ethylene Glycol) Spacers

“…In general, they exhibit maxima absorption wavelength close to those reported for similar push-pull azo-compounds [11,12]. In these materials, both Jand H-type aggregation have been observed in casted films [10].…”

“…In the last years, various azopolymers bearing amino-nitro-substituted azobenzene units, such as those of the pnMAN series, have been synthesized and characterized [10]. In general, they exhibit maxima absorption wavelength close to those reported for similar push-pull azo-compounds [11,12].…”

Holographic Information Media Based on Azo-Polymers with Different Structures

“…Nd 3+ : YAG laser with light wavelength λ=532 nm and maximal power 100 mW was used. Usual setup for registration of the holograms of fl at wave front [9,13] was used in the experiments. Kinetics of recording and relaxation of the holographic gratings for the both cases mutually parallel and perpendicular polarization vectors of recording and reference light beams are shown in Figure 3.…”

Photo Alignment Behaviour of Polyethene Imine Having Cyano Azobenzene Side Chain

“…Therefore, the irradiation of light in this wavelength region should cause the photoisomerisation from the transform to the cis-form and vice-verse for the cis-form. Consequently, trans-cis-trans photoisomerisation cycle of PEI6C will be brought about by irradiation of the light in this region [15][16][17] .…”