Influence of the molecular structure of polyurethane acrylates on the morphology and properties of polymer dispersed liquid crystals
Polymer dispersed liquid crystal(PDLC)is a composite material formed by uniform dispersion of liquid crystal domains within a polymer matrix.Because of its simple preparation and no need for polarizer and orientation layer,it has a wide range of application prospects in the fields of smart windows,flexible displays and wearable devices.In order to broaden its application scenarios in flexible display devices,this paper uses polyurethane acrylate(PUA)oligomers as the polymer matrix to prepare PDLC devices by ultraviolet photopolymerization.The effect of the molecular structure of PUA on the morphology and properties of polymer dispersed liquid crystals is investigated.The results show that the speed of the polymer monomer polymerization with acrylate groups for capping is fast,forming a polymer mesh-like structure,and the size of the polymer mesh decreases gradually with the change of the molecular structure from aliphatic to aromatic,resulting in an increase in the driving voltage of PDLC.The hydrogen bonding formed between the molecular chains by utilizing the urethane urethane bonding enhances the adhesion with the plastic substrate,thus obtaining PDLC devices with excellent overall performance.Compared with the aromatic PUA,the PDLC samples prepared from aliphatic PUA are characterized by lower driving voltage(Vth=9.14 V,Vsat=35.50 V),higher contrast(CR=73.25),better adhesion(20.11 N/cm2),and smaller changes in the optoelectronic properties before and after bending at a bending radius of 4 cm.
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