Study On Photoinduced Bending Liquid Crystal Functional Materials Containing Azobenzene

Liquid-crystalline elastomers(LCEs)combine the anisotropy of liquid crystal(LC) and elasticity of polymer network,enabling them to show excellent mechanical property,thermal stability and chemical stability.In this disseration,azobenzene LC monomers with different structures were synthesized.Two kinds of novel azobenzene LC functional materials were fabricated.Azobenzene LC monomers were synthesized and their thermodynamics and LC properties were characterized with DSC and POM.The two monomers M6AB2 and M11AB4 show no LC property,but monomer 5CAZ has a high phase-transition temperature and the obvious nematic texture.UV-light response of three azobenzene monomers was characterized by UV-Vis absorption spectroscopy.Their maximum absorption peak showed red shift.The structure and properties of azobenzene-containing random copolymers were characterized by ~1HNMR,GPC,DSC and POM.LCE fibers were prepared by melt drawing and post-crosslinking with high degree of orientation and the azobenzene groups in the side chain.Upon UV-light irradiation,LCE fibers bend away from light source,which is far different from previously-reported results.It can spontaneously return to the initial state at high temperature,concentration of azobenzene and temperature has an important effect on the photoresponsive behavior of LCE fibers.Based on the polymer-dispersed liquid crystal(PDLC)system,NIR-VIS-UV light responsive PDLC/GO composite film was fabricated.Fast photoinduced deformation of the composite film was realized due to photothermal effect of GO upon NIR or VIS light irradiation.Benefiting from the doping of one azobenzene dye(5CAZ)in the LC microdomains,photochemical phase transition was obtained isothermally,endowing the PDLC composite film with UV-light response.Direct exposure to nature sunlight,the film demonstrated quick photomechanical behaviors.