| Liquid crystal elastomer(LCEs)is a kind of bidirectional memory deformable material with stimulus-response properties.Its molecular structure is formed by the alternating arrangement of rigid and flexible molecules,which is highly ordered and controllable.Liquid crystal elastomer can be deformed under the action of temperature,pressure,electric field,light field,and another external energy field,so it is widely used in software robots,artificial muscles,micro-nano machinery,and other fields.Among them,the light response liquid crystal elastomer software robot can use the photothermal effect or photochemical effect of intelligent deformable materials to transform light energy into its mechanical deformation and motion and has the advantages of remote driving and fast response.It is helpful to solve the problems of poor flexibility and low driving efficiency of existing software robots.Therefore,in this paper,we develop a spider web-like nano-silver liquid crystal elastomer with high photothermal conversion efficiency,high energy density,and fast deformation control,and use it as a flexible driving material.A new type of bionic tailless driving and fast response optical drive software robot is developed.The main research progress of this paper is as follows:(1)Using silver nanowire solution as a precursor,mask electrospinning technology was used to form a three-dimensional network high thermal conductivity path imitating spider web on the surface of liquid crystal elastomer,and to construct nanocrystalline silver liquid crystal elastomer with anisotropic photothermal structure imitating spider web.The influence and synergistic mechanism of different silver nanowire network structures and near-infrared light fields on the heating rule under near-infrared radiation were explored.The experimental results show that with the increase in the complexity of constructing a silver nanowire network and the increase of near-infrared light intensity radiation,the photothermal conversion efficiency of nano-silver liquid crystal elastomer is gradually improved,and the photothermal conversion efficiency of LCE2can reach 25.09%.(2)The thermomechanical strain behaviors of liquid crystal elastomers with different spider web-like three-dimensional silver wire networks with high thermal conductivity were studied to explore the variation law of temperature-strain,and the effect of nano-silver wire network structure on the thermotropic deformation of liquid crystal elastomers was analyzed.Combined with the temperature-strain variation law of nano-silver liquid crystal elastomers under different loads,the strain evolution mechanism of nano-silver liquid crystal elastomers was revealed.The experimental results show that with the increase of the complexity and load of the silver nanowire network,the shrinkage of the silver nanowire liquid crystal elastomer increases significantly.When the load is 30m N,the maximum shrinkage of Ag Nps LCE2 is2010.46um,and the shrinkage strain can reach 10.31%;when the load is 150m N,the maximum shrinkage of Ag Nps LCE2 is 2167.24um,and the shrinkage strain can reach11.12%.In the artificial muscle experiment,the nanometer silver liquid crystal elastomer can increase 105g weight(42 times its weight)under near-infrared radiation,and the energy density is 11.65J/Kg.(3)The photo deformation behavior of nano-silver liquid crystal elastomer imitating spider-web three-dimensional network nanowire-silver with high thermal conductivity was studied.To explore the change law of near-infrared light field parameters-bending deformation,to investigate the effect of nano-silver wire network structure on the photo deformation of liquid crystal elastomers,and to explore the regulation mechanism of bending deformation of nano-silver liquid crystal elastomers.The experimental results show that the nano-silver liquid crystal elastomer can bend upward and downward by adjusting the radiation position of the near-infrared light.Among them,under the radiation of light intensity of 3.54W/cm~2,the nano-silver liquid crystal elastomer actuator performs upward and downward bending movements at an upward bending rate of 9.54/s,a temperature rise rate of 6.87℃/s and a downward bending rate of 7.32/s and a temperature rise rate of 8.28℃/s,respectively.(4)The optical driving experimental platform is built,and the nano-silver liquid crystal elastomer bionic software robot with symmetrical structure,asymmetric structure,and Janus structure is designed and driven by 3.54W/cm~2 light intensity radiation to explore the motion law of different bionic structure software robot based on anisotropic friction in the near-infrared light field.Experiments show that the bionic liquid crystal elastomer software robot has an excellent light response and fast actuation performance.Among them,the symmetrical structure software robot moves forward at the rate of 4.69mm/s;the asymmetric structure software robot moves forward at the rate of 3.99mm/s;the Janus structure software robot can realize omnidirectional movement forward and backward,for example,the light source moves from right to left to illuminate the Janus structure software robot,and the Janus structure software robot can move to the right at the speed of 3.48mm/s.When moving from left to right,the Janus structural software robot can move to the left at a speed of 1.29mm/s.The bionic liquid crystal elastomer software robot with photothermal deformation studied in this paper can accurately drive and control it through the external light field and is expected to enter a narrow and limited space to carry out tasks,which is expected to promote the further development of the software robot field. |
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