Synthesis And Properties Of Triphenylamine-Containing And Fluorinated Structures And Asymmetric Polyimides Containing Ester Bonds

Traditional aromatic polyamides are widely accepted as advanced materials in the fields of thin films,petrochemicals,aerospace and other fields in microelectronic devices and liquid crystal displays due to their excellent mechanical,chemical,thermal and physical properties.However,due to their rigid backbone,high melting point temperatures or Tg and limited solubility in most organic solvents make these polymers difficult to process,technical applications are limited.In order to overcome these limitations,polymer structural modification becomes necessary.There are several methods to improve the solubility and machinability of polyimides and polyimides without reducing the high thermal stability of polyimides,such as introducing large side groups into polymers,filling destructive groups or kinking structures,introducing ether bond or ester bond,introducing fluorine atoms,introducing asymmetric fragments to reduce the interaction between molecules,and so on.In the past few years,fluorine-containing polyimides have received increasing attention from the outside world,especially polyimides containing trifluoromethyl groups.The introduction of fluorine atoms into polyimide molecules can make polyimides.The overall polarizability of the oligomer is reduced,which weakens the inter-molecular force of the polyimide.The introduction of fluorine atoms increases the spacing and free volume between the polyimide molecules to a certain extent,so that the solvent is more permeable to the polyimide molecules,thereby improving the solubility thereof.Moreover,The fluorine atom has a very strong electronegativity,which reduces the conjugation of the polyimide benzene ring to the imide ring,thereby reducing the charge transfer?CTC?effect between the polyimide molecules,thereby increasing the polyamido.The light transmittance of the amine reduces its dielectric properties.The introduction of a geometric or molecularly asymmetric diamine component into the polyimide backbone to form a new polyimide can increase properties such as solubility and melt processability,and the introduction of ester-bonded flexible groups to a certain extent It is also possible to improve the solubility of polyimide.In view of the above research background,this article will explore the following two parts:Part ?:We use aniline and 3,5-ditrifluoromethylaniline as starting materials to prepare two diamine monomers containing trifluoromethyl group and no trifluoromethyl group by two reactions,4,4'-Diaminotriphenylamine,4,4'-diamino-3'',5''-ditrifluoromethyltriphenylamine.They were polymerized with ODPA,6FDA,BTDA three dianhydrides to obtain two series of polyimides,named PI₁^PI₃ and FPI₁^FPI₃,and two series of polyimide materials.The performance is tested.We have found that the introduction of the trifluoromethyl group of the novel polyimide material not only has excellent solubility and hydrophobic properties,but also a slight decrease in the melting temperature is beneficial to the processing of the material,and the introduction of trifluoromethyl groups The machinability of the material being maintained,and finally the material also has stable electrochemical properties.Polyimide has good film formation,high HOMO content,long-term redox and electrochemical reversibility.Therefore,these polyimides may be used as new hole transport materials due to their appropriate HOMO values and their use as optoelectronic applications.Part ?:We synthesize 4-?4-aminophenoxy?phenyl-4-aminobenzoate,a diamine monomer containing an asymmetric fragment of an ester group,using p-nitrobenzoyl chloride as a raw material.Then,it is blended with diamine monomer ODA,dianhydride monomer ODPA or BTDA in a ratio of 20%,40%,60%,80%,100%to obtain a polyimide,which is named OPI₁^OPI₆ and its performance were tested.We found that the new polyimide material prepared by introducing an asymmetric segment containing an ester bond into the polyimide material maintains the good mechanical strength of the conventional aromatic polyimide material.And heat resistance,and has excellent light transmittance and solubility,this material has potential application in the field of liquid crystal display and microelectronics.