液晶弹性体.ppt

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1、Actuators Based on Liquid Crystalline Elastomer(LCEs)MaterialsContents1.Introduction2.What is LCEs3.Actuators based on LCEs 3.1.Actuators based on thermally actuated LCEs 3.2.Actuators based on photo-mechanically actuated LCEs 3.3.Actuators based on photo-thermo-mechanically actuated LCEs4.Summary 1

2、.IntroductionSmartMaterialsCondutingpolymerliquid crystal elastomershydrogelpiezoelectricsShape memory alloy/polymerFig 1.Fig 1.The diferent kinds of actuator materials both in natural and synthetic systemsSmart materials:There is a group of materials capable of responding to external stimuli with m

3、echanical deformation.LCEs:LCEs:LCEs are novel materials among the polymer smart materials.They have properties of both liquid crystals and elastomers:the self-organization nature of liquid crystal systems and the flexibility stemming from the elasticity of polymer networks allow for large and rever

4、sible anisotropic dimensional changes in response to applied stimuli.2.What is LCEs LCEs are cross-linked polymer networks that contain rigid,anisotropic mesogenic units mesogenic units incorporated into the polymer chainspolymer chains.Due to the anisotropic nature of these units,the materials exhi

5、bit a liquid crystalline structure in which the mesogenic units have a certain orientational order but remain individually mobile and thus could flow with respect to one another.YZXRRMNMesogenic unitK K107 N N116 I IExample:(a)(b)(c)Fig 2.Fig 2.Schematic representation of different types of LCEs:(a)

6、main chain LCEs;(b)side chain LCEs;(c)combined LCEs3.Actuators based on LCEs 3.1.Actuators based on thermally actuated LCEsFig 3.Fig 3.Micrometer-sized nematic LCE actuators consisting of a pillar array.(a)Experimental setup used to prepare the responsive pillars.(b)Top view(under an optical microsc

7、ope)of the pillar pattern obtained by the imprint in the nematic liquid crystal elastomer.(Inset)Zoom on the structure(pillar diameter=20mm)1.1 Buguin A,Li M H,Silberzan P,et al.Journal of the American Chemical Society,2006,128(4):1088-1089.3.2.Actuators based on photo-mechanically actuated LCEs3.Ac

8、tuators based on LCEs Fig 4.Fig 4.(a)A schematic representing the assembled prototype of a micropump.(b)Photo of the experimental prototype(1)inlet,(2)press plate,(3)photodeformable material,(4)outlet,(5)pump membrane,and(6)pump chamber).(c)The photodeformable film on the pump membrane(1)press plate

9、,(2)photodeformablefilm,(3)pump membrane,and(4)pump chamber).22 Chen M,Xing X,Liu Z,et al.Applied Physics A,2010,100(1):39-43.3.Actuators based on LCEs Fig 5.Fig 5.A light-driven plastic motor with an LCE laminated film.(a)Schematic illustration of a light-driven plastic motor system,showing the rel

10、ationship between light irradiation positions and rotation direction.(b)Series of photographs showing time profiles of the rotation of the light-driven plastic motor with the LCE laminated film induced by simultaneous irradiation with UV(366 nm,240 mW cm-2)and visible light(500 nm,120 mW cm-2)at roo

11、m temperature 33 Yamada M,Kondo M,Mamiya J,et al.Angewandte Chemie International Edition,2008,47(27):4986-4988.3.Actuators based on LCEs 3.3 Actuators based on photo-thermo-mechanically actuated LCEsFig 6.Fig 6.Optical images of photo-actuation of a blank LCE and an SWCNTLCE nanocompositefilm.The fi

12、lms have dimensions of 4 cm 0.5 cm0.7 mm.The irradiation intensity of the white light is 230 mW cm-2.(a)The initial state of the blank LCE and SWCNTLCE nanocompositefilms.(b)Comparison of the two films under irradiation.The blank LCE does not deform after being illuminated for several minutes.In con

13、trast,the SWCNTLCE nanocompositefilm starts to contract conspicuously after about 5 seconds,and reaches the stable length,which is about 2/3 of the initial length,after about 10 seconds.(c)The SWCNTLCE nanocomposite film recovers to its initial length in about 9 seconds after the light source is swi

14、tched off.4.Summary LCEsLCEs are particularly promising materials for artificial muscles,micro-robots and MEMS.In these systems not only 2D but also 3D motion has now been achieved,and a variety of actuation modes have been developed,which are competitive and promising for many applications as soft actuators.Thanks for your attention Thanks for your attention!