Expansion And Rotation Behavior Of Nematic Liquid Crystal Elastomer Balloon Induced By Inflation

Smart material is a new type of functional material,which has been developing rapidly since the 1990 s.Different from the traditional materials with single performance and function,smart materials refer to the intelligent materials with the characteristics of sensing the environmental stimulus,analyzing,processing and judging it,and taking certain measures to respond appropriately.Liquid crystal elastomer is a new kind of polymer smart material.The liquid crystal elastomer has dual properties of liquid crystal and elastomer due to its special molecular structure.The flexibility brought by the self-organizing properties of liquid crystal systems and the elasticity of polymer networks allows them to produce large and reversible anisotropic dimensional changes under applied stimuli.Under the action of uniaxial tension,the liquid crystal monomer inside the nematic liquid crystal elastomer membrane rotates and then causes shearing inclination at both ends of the membrane.The shearing effect induced by this simple action has potential applications in artificial muscle,nano devices and biomedicine.When the liquid crystal elastomer film is made into a balloon as an artificial muscle,it shows a strange inflatable behavior.At the same time,the liquid crystal elastomer balloon may also have shear rotation effect due to the rotation of the initial inclined liquid crystal monomer during the inflatable process.The reorientation of the liquid crystal elastomer leads to the macroscopic deformation of the elastomer.Under different axial tension,the balloon inflates with a variety of behaviors of rotation and expansion.Based on the basic elastic theory of nematic elastomer,the rotation behavior and mechanism of a nematic liquid crystal elastomer balloon with an inclined liquid crystal element under the combined action of axial stretching and inflating are studied and revealed for the first time.This paper behaves as follows.Firstly,the balloon model of nematic liquid crystal elastomer with tilted liquid crystal monomer is established,and the governing equation is derived.Then,the changes of the ring direction,axial direction,volume,inclination Angle and rotation Angle of the liquid crystal monomer during the inflating process are obtained by numerical solution.By drawing and analyzing the numerical results of the calculation,the final conclusion is drawn.The results show that the axial force and the initial inclination Angle of the liquid crystal monomer have important effects on the aeration behavior.When the axial force is small,there is a critical initial dip Angle.When the initial inclination is less than the critical Angle,the inflating behavior is similar to that of a conventional balloon.When the dip Angle is larger than the critical Angle,it shows strange bubbling behavior.The induced rotation Angle has a maximum value.When the axial force is large,there is a small and a large critical initial inclination.When the initial inclination Angle is between two critical angles,the balloon shows strange bubbling behavior.At other initial angles,the inflating behavior is similar to that of a conventional balloon.In this process,the induced rotation Angle also has a maximum value.The results of this study further deepen the understanding of the deformation behavior of the nematic liquid crystal elastomer balloon,and provide guidance for its application in artificial muscle and soft robot.Figure:[45],Reference:[77]...