蓝相液晶

蓝相液晶BluePhases作者：车向阳学号：2014432001OUTLINE•Thehistoryofthediscovery•Definition•Classification•Characteristic•StructureofBP•ProspectsfordevelopmentThehistoryofthediscovery•in1888：Asacholestericcompoundslowlycoolsfromtheisotropicphase,bluescatteringcanbeseenmomentarilyimmediatelypriortothephasetransitiontothechiralnematic(cholesteric)phase.•in1956：CoatesandGraycameupwiththename,“bluephases”,toindicatethisunusualstate,andbegantotreatthephaseasoneoftheliquidcrystalphases•between1970and1990：thestudyofbluephaseabruptlybecamepopular,particularlyinthefieldofphysicsDefinition•Bluephasesareliquidcrystalphasesthatappearbetweenchiralnematicphaseswithrelativelyshorthelicalpitchesandisotropicphases.Classification•Therearethreekindsofphases,bluephaseI(BPI),bluephaseII(BPII),andbluephaseIII(BPIII),inorderofincreasingtemperature•BPIhasbody-centeredcubicsymmetry•BPIIhassimplecubicsymmetry•TheunitlatticesofBPsIandIIhavealatticeparameterofapproximately200to300nm,withBraggdiffractionintheultravioletandvisibleregion.•BPIIIhasisotropicsymmetry（unknown)ThechangeoftemperaturerisingprocessCharacteristic•Lightinthevisiblepartofthespectrumistochoosethescattering,accordingly,Thisphaseappearsbrightblue,thebluephaseandhencethename;•Bluephaselinearbirefringencecan'thappen,itiswithopticalanisotropy•NMR(nuclearmagneticresonance(NMR)spectroscopy)indicatebluephasespectrallongrangeandorderly,andNMRspectraofbluephaseisbothdifferentfromthatofisotropicphaseNMRspectrumandalsodifferentfromNMRspectrumofcholestericphase•Noteverykindofmaterialcanbeobservedinthethreephase;•PitchisgreaterthanthecriticalpitchpccholestericphaseliquiddoesnotexistBluephase;StructureoftheBPComparedwithordinarychiralnematicphase,thebluephasewithdoubletwiststructure单扭曲结构中，同一切面内的分子排列一致，如果分子在切面内也发生旋转的话，会形成稍微复杂一些的双扭曲结构。“双扭曲”和“单扭曲”结构的区别在于，双扭曲结构在单扭曲结构的基础上，在同一平面内的相邻分子的取向也会发生旋转。•完全的双扭曲排列只能•在中心分子及其附近形•成，越往外围伸展双扭•曲排列越不稳定，因此•分子的双扭曲排列在空•间中排列形成双螺旋柱。•由于双螺旋柱不能够•连续占据三维空间，所•以当这种结构在三维空•间中伸展后，将不可避•免地会产生缺陷，这些•缺陷的产生包含着一定•的能量，从而使整个分•子排列变得不稳定，因•此当双扭曲排列稳定存•在时，体系中必须存在很强的扭曲力，扭曲力越强,双扭曲排列越稳定，所以蓝相一般存在于具有很强手性的体系中。•。•蓝相是由双扭曲和缺陷共存形成的体系，形成缺陷会损失一定的能量，而形成双扭曲则会产生一定的能量，并且形成双扭曲产生的能量用以中和形成缺陷所损失的能量，从而形成稳定的蓝相ProspectsfordevelopmentThedefectsofthebluephaseliquidcrystal•BP-LConcefacingtheseriousproblemisthebluephasetemperaturerangeistoonarrow,usuallyonly1℃orso.Butwiththediscoveryofstablepolymerbluephaseliquidcrystal,BP-existingtemperaturerangehasexpandedtoLC-10~50℃butstillfacesthefollowingtwoquestions:•Thefirst：Thedrivingvoltageistoohigh•Thesecond：Transparencyisnothigh,onlyabout65%thankyou