Synthesis And Properties Of Multilayer Polysiloxane Liquid Crystal Elastomer And Luminescent Liquid Crystal Materials

Under the stimuli of external conditions such as sun-light and humidity,vine plants can reversibly change their posture and climb outwards on external objects.Its motion posture can be decomposed into two fundamental modes,bending and chiral twisting(left-handed or right-handed distortions).To date,according to these biological mechanismsmany,artificial plant-like devices have been developed.However,previous studies have faced a huge challenge:the left-handed spiral and the right-handed spiral can not appear in the same material,but also can not realize the mutual transformation of the motion mode under different stimulation conditions.In this work,we design and synthesize liquid crystal monomer MBB,crosslinker 11UB,photothermal dye YHD796,oil-soluble gold nanoparticles AuNPs,and use the commercial dye Dye1002 reported in the literature as a filler.Two-layer and three-layer polysiloxane liquid crystal elastomer composites were successfully prepared by Finkelmann's two-step crosslinking process.The multi-stimuli response behaviors of these composite materials are investigated under visible light,near-infrared light and infrared light.In the prepared two-layer liquid crystal elastomer composite film,when the long axis direction of the film is parallel to the orientation direction,the material is bending deformation.When the longitudinal direction of the film is at an angle of 45~o to the orientation direction,the material is spirally deformed.In the three-layer liquid crystal elastomer composite film,the purpose of producing two kinds of deformations(upper arch and lower arch)on the same material is achieved.However,the three-dimensional deformation-double helix can not be realized,and only a combined deformation between a single helix(left-handed or right-handed)and a curved behavior can be achieved.Therefore,another research work has been carried out.The newly emerging aggregation-induced emission(AIE)theory provides a striking perspective to synthesize luminescent liquid crystal(LLC)materials with outstanding solid-state luminescence properties which have exhibited prosperous applications in semiconductor materials,liquid crystal displays and organic light-emitting diodes.However,up to now,all the known AIE-active LLC molecules are based on very limited AIE fluorophores including cyanostilbene,tolane and tetraphenylethene cores.In this work,we design and synthesize two categories of tetraphenylthiophene-core disk-like molecules,TPTn bearing one tetraphenylthiophene-core and eight peripheral alkoxyl chains,and TPTEn bearing one tetraphenylthiophene-core and four 3,4,5-trialoxybenzoate groups,which can form the square columnar,rectangular columnar or hexagonal columnar phases depending on the mesogenic core structures and the chain length of the aliphatic tails.Meanwhile,these tetraphenylthiophene-core LLC molecules exhibit obvious AIE characteristics,the fluorescence emission intensity values measured in aggregated state were hundred times higher than those values presented in benign solvents.Furthermore,the narrow band gap energies of these synthesized discotic LLC molecules will benefit electric charge transmission,which might have potential applications in organic semiconductor materials.