Phase Structure And Photodeformable Behavior Of Liquid Crystal Polymers Based On Azobenzene Rigid Main Chain

In this thesis,we focus on the liquid crystal properties,phase behavior,phase structure and photo-responsive of azobenzene liquid crystal monomers and polymers.As a result,the content mainly includes following several aspects.1.A series of monomers contain azobenzene Mms(m is the length of the alkyl tail and m=4,6,8,10,12)with different alkyl tail lengths are designed and synthesized.And the NMR(1H NMR and 13C NMR)and FTIR are employed to confirm the chemical structures of Mms.The phase behavior and phase structure of these monomers are characterized by POM,DSC and 1D WAXD.The monomers Mms without a clearing point temperature show crystal structure during the low tempereature and a stable smectic phase order structure in high temperature.Furthermore,M8 is doped into 5CB to extend the liquid crystal range of 5CB and induce 5CB orientation.2.The corresponding polymer Pms(m is the length of the alkyl tail and m=4,6,8,10,12)are successfully synthesized via conventional radical polymerization.The structures and characteriztion of the polymers were confirmed by 1H NMR and GPC.And the thermal stability,phase behavior and phase structure of the polymers are characterized by TGA,DSC,POM and 1D WAXD.The experiments results show that polymers present excellent thermal stability and form lamellar phase,tetragonal columnar phase and hexagonal columnar phase depended on their alkyl tails.3.Random copolymer PHCS-co-P8n(Sns,n=1,2,3,4)are successfully synthesized using the designed monomers M8 and di(hexyl)vinylterephthalates(HCS)via radical polymerization.1H NMR and GPC results indicate the relative molecular weight and content of different components.TGA,POM,DSC and 1D WAXD are used to explore the thermal stability,phase behavior and phase structure.The experiments results show that a series of Sns(n=1,2,3,4)present excellent thermal stability and a columnar nematic phase.Moreover,melt drawing and hot-pressing can be used to prepare the photoinduced-deformable actuator with presented the well photoinduced deformation.At the same time,the samples prepared in two ways exhibit the absolutely opposite photoinduced-deformable behavior by alternate irradiation of ultraviolet and visible light.