Regulating The Photodeformation Performance Of Side-chain Liquid Crystal Elastomers By Copolymerization

Photodeformable liquid crystal elastomer is a type of intelligent material with light response performance.It has a very wide range of applications(flexible robot,artificial muscle,microfluidic control,etc.).Because light has many advantages,such as no pollution and adjustable performance parameters,so it has gradually became a research hotspot in smart materials.The light response performance of the common photodeformable liquid crystal elastomer is unregulated.So seeking a way to adjust its photodeformation performance is important.Nowadays,copolymerization has been used as an effective method for regulating the properties of polymer materials.According to the properties of the materials,the chemical mechanism and molecular interactions within the polymer could be changed by copolymerization,so as to effectively control the properties of the material,such as crystallinity,solubility,glass transition temperature and the like.This thesis is focused on the influences of liquid crystalline(LC)phase behavior and phase structure on the photoresponsive properties of side chain liquid crystalline elastomers(SCLCEs).Change different light-responsive groups and introduce different third monomers,second types of liquid crystal elastomers with azobenzene or cyanostyrene as photoresponsive elements were synthesized by copolymerization.And we used different test methods to study its photophysical properties,phase structure,etc.This article mainly presents the following three aspects:1. Monomers were designed and synthesized:(E)-10-(4-((4-(dodecyloxy)phenyl)diazenyl)phenoxy)decyl methacrylate(M10DAB12),2-(6-(6-methyl-4-(1-hydrogen)-pyrimidinone)-urea-hexamethylene carbamate)ethyl methacrylate(ME6UPy),10-((4'-(dodecyloxy)-[1,1'-biphenyl]-4-yl)oxy)decyl methacrylate(M10B12).A series of hydrogen bonded crosslinked DAB-based SCLCEs(DAB(m)-Py(0.06)-BP(n)(m:n=0:5,1:4,2:3,3:2,4:1,5:0))with different DAB contents were successfully synthesized via conventional free radical polymerization.The effect of biphenyl element contented on the liquid crystal properties and photodeformation properties of DAB-based SCLCEs was studied.Thermogravimetric analysis(TGA)result showed that DABm-BPn had good thermal stability.The DSC,POM,and 1D WAXD results showed that all the DAB(m)-Py(0.06)-BP(n)samples formed smectic phase.With the introduction of biphenyl mesogens,both T_g and of DAB(m)-Py(0.06)-BP(n)showed some extent of the decrease due to the structural differences between azobenzene and biphenyl.Optical physical performance test showed that DAB(m)-Py(0.06)-BP(n)had obvious isomerization reaction.Photoisomeric performance test showed that the maximum bending angle of single domain oriented fiber showed a decreasing trend after increasing.2. Monomer(Z)-10-(4-(1-cyano-2-(4-cyanophenyl)vinyl)phenoxy)decyl methacrylate(M10PVPCN)was designed and synthesized.A series of hydrogen bonded crosslinked CN-based SCLCEs(CN(m)-Py(0.06)-BP(n)(m:n=0:5,1:4,2:3,3:2,4:1,5:0))with different CN contents were successfully synthesized via conventional free radical polymerization.The effect of biphenyl element contented on the liquid crystal properties and photodeformation properties of CN-based SCLCEs was studied.Thermogravimetric analysis(TGA)result showed that CNm-Py(0.06)-BPn had good thermal stability.The DSC,POM,and 1D WAXD results showed that CN0-Py(0.06)-BP5,CN(1)-Py(0.06)-BP(4),CN(2)-Py(0.06)-BP(3),CN(3)-Py(0.06)-BP(2)formed smectic phase,and CN(4)-Py(0.06)-BP(1),CN(5)-Py(0.06)-BP(1)formed nematic phase.With the introduction of biphenyl mesogens,both T_g and of CN(m)-Py(0.06)-BP(n)showed some extent of decrease due to the structural differences between?-cyanostilbene and biphenyl.Optical physical performance test showed that CNm-Py(0.06)-BPn had obvious isomerization reaction.Photoisomeric performance test showed that the maximum bending angle of single domain oriented fiber showed a decreasing trend after increasing.And a small amount of biphenyl would make CNm-Py(0.06)-BPn have a large maximum bending angle.Finally,we explored and found that this series of elastomers had shape memory properties.3. A series of hydrogen bonded crosslinked CN-based SCLCEs(CN(m)-Py(0.06)-BMA(n)(m:n=0:5,1:4,2:3,3:2,4:1,5:0))with different CN contents were successfully synthesized via conventional free radical polymerization.The effect of butyl methacrylate element contented on the liquid crystal properties and photodeformation properties of CN-based SCLCEs was studied.Thermogravimetric analysis(TGA)result showed that CNm-Py(0.06)-BMAn had good thermal stability.The thermal decomposition temperature of SCLCEs decreased with butyl methacrylate element increased.The DSC,POM,and 1D WAXD results showed that all the CNm-BMAn samples formed nematic phase.Optical physical performance test showed that CNm-Py(0.06)-BMAn had obvious isomerization reaction.Photoisomeric performance test showed that the maximum bending angle of single domain oriented fiber showed a decreasing.It could be seen that butyl methacrylate had a significant plasticizing effect on the CNm-Py(0.06)-BMAn.Finally,we explored and found that this series of elastomers had shape memory properties.