| Liquid crystal elastomer is a new kind of intelligent material,which can deform reversibly under external stimulation(such as heat,light,electric field,magnetic field,etc.),and has good thermal stability and mechanical properties.Light energy has the characteristics of environmental protection,no contact,adjustable performance parameters,low cost,and wide source,so photoresponsive liquid crystal elastomers can stand out from many stimulus responsive liquid crystal elastomers.This material contains different kinds of photosensitive groups,which can absorb light at specific wavelengths,and the photoisomerization reaction will be induced by light stimulation.Among them,the azobenzene photosensitive group has always been a hot research topic.Researchers can pre-engineer photoresponsive elastomer materials to perform motion patterns such as elongation,contraction,bending,and rotation.Nematic liquid crystal elastomers are often made into balloons and used in artificial organs,soft robots,and other fields.In the past few decades,researchers have discovered many phenomena related to the balloon deformation of liquid crystal elastomers and developed theoretical models for photoinduced deformation of liquid crystal elastomers.Although there is much research on the deformation of liquid crystal elastomer balloons,the research on the rotation and shear behavior of liquid crystal elastomer balloons under light stimulation is not thorough enough,and the theoretical model is lacking,which limits the application of photoresponsive liquid crystal elastomer balloon in biomedical,electronic engineering and other fields.In this paper,the phenomenological relationship between light intensity and material parameters in the process of photoresponsive liquid crystal elastomer balloon deformation is deduced,a new theoretical model of photoresponsive liquid crystal elastomer is established,and the photoinduced deformation behavior of liquid crystal elastomer balloon with and without axial load and different light intensity is studied theoretically.The research work of this paper is as follows:(1)Firstly,the concept,classification,preparation method,and optical deformation mechanism of liquid crystal elastomers are introduced in detail.(2)Some basic theories of nematic phase elastomer are sorted out and based on these theories,the optical drive model of nematic phase liquid crystal elastomer balloon is established,and the corresponding governing equations are derived and numerically solved.(3)The variation data of each physical quantity during the balloon deformation of free nematic liquid crystal elastomer are obtained by numerical solution,and the corresponding relationship diagram is drawn according to these data.The photostriction and rotation behavior of free nematic liquid crystal elastomer balloon under different illumination intensity and different initial inclination Angle of liquid crystal element are studied by these illustrations,and the conclusion is drawn.(4)The deformation behavior of nematic phase liquid crystal elastomer balloon under axial load was theoretically analyzed,its governing equation was numerically solved,and the photostriction and rotation behavior of nematic phase liquid crystal elastomer balloon under axial load were studied under different illumination intensity and different initial inclination Angle of liquid crystal element.The conclusions of this paper are as follows:(1)The results show that both the illumination intensity and the initial inclination Angle of the liquid crystal element have a great influence on the deformation behavior of the free nematic liquid crystal balloon.When the initial inclination Angle of the liquid crystal element is equal to or not equal to zero,the deformation characteristics of the balloon have a great difference.When the light intensity is large enough,the balloon no longer shear,the upper and lower cross sections do not rotate relative,and the polymerization backbone chain of the liquid crystal elastomer changes into isotropy.(2)Axial load on the deformation behavior of liquid crystal elastomer balloon complex effects,under the action of axial load,the balloon under different constant your three completely different photoresponse deformation behavior,the balloon deformation under moderate your behavior is more complex,with the increase of volume of the balloon,when the air pressure inside the balloon to maxwell stress,The balloon will appear local bubbles,after that,with the increase of the air volume inside the balloon,the bubbles will continue to spread until the balloon is completely bubbling.The bubble propagation can be promoted by increasing light intensity,and the change of light intensity can promote the phase transition between uniform and non-uniform states of the liquid crystal elastomer balloon.In this paper,the photodeformation behavior of nematic liquid crystal elastomer balloons is studied,which can provide ideas for the applications of nematic liquid crystal elastomer materials in soft robots,artificial organs,biomedicine,and other fields.Figure:[55] Reference:[79]... |
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