Synthesis Of Diamine Monomer And Preparation Of Polyimide Containing Triazine Structure

In this paper,the synthesis of two new monomers containing triazine diamine2,4-diamino-[N,N'-bis?4'-p-aminobenzylphenyl?]-6-phenyl-1,3,5-triazine?DBAPPT?and2,4-diamino-[N,N'-bis?4'-amino-3,2'-dimethylbiphenyl?]-6-phenyl-1,3,5-triazine?DBADPP T?were studied.Through the orthogonal experiment,the optimum reaction conditions for the synthesis of DBAPPT were obtained as follows:the reaction temperature was 160 ^oC,the reaction reflux time was 4 h,the amount of 4,4'-diaminodiphenyl methane?DDM?was8 times as the amount of 2,4-dichloro-6-phenyl-1,3,5-triazine,the amount of anhydrous sodium carbonate was 3 times as the amount of 2,4-dichloro-6-phenyl-1,3,5-triazine material,and the yield could reach as high as 95.56%.The structure of the product was characterized by FT-IR and ¹H-NMR,the melting point of the monomer was 184.64 ^oC determined by DSC,and the purity of the product measured by HPLC was 97.45%.The optimum reaction conditions for the synthesis of DBADPPT are as follows:the amount of m-Tolidine was 8 times as the amount of 2,4-dichloro-6-phenyl-1,3,5-triazine,the dripping time of the mixed solution of 2,4-dichloro-6-phenyl-1,3,5-triazine and 1,4-dioxane was 40min,the reaction reflux time was 6 h,the amount of anhydrous sodium carbonate was 3times as the amount of 2,4-dichloro-6-phenyl-1,3,5-triazine material,and the yield could reach as high as 89.24%.The structure of the product was characterized by FT-IR and¹H-NMR,the melting point of the monomer was 223.68 ^oC determined by DSC,and the purity of the product measured by HPLC was 94.26%.A series of polyimide moulding powders were prepared by reacting DBAPPT with2,3',3,4'-biphenyl tetracarboxylic dianhydride??-BPDA?,4,4'-?4,4'-isopropylidene-diphenoxy?-bis-?phthalic anhydride??BPADA?,3,3',4,4'-biphenyl tetracarboxylic dianhydride?BPDA?,4,4'-oxydiphthalic anhydride?ODPA?and 3,3',4,4'-benzophenone tetracarboxylic dianhydride?BTDA?,respectively.The results show that the moulding powder had been iminated completely,and the Tg of the moulding powder was 189.50^oC²36.45 ^oC.Under N₂,the corresponding temperature of 5%weight loss was 484.4^oC⁵05.8 ^oC,the corresponding temperature of 10%weight loss was 512.9 ^oC⁵21.6 ^oC,the carbon residue rate at 800 ^oC was 54.37%⁵7.81%.Under the air,the corresponding temperature of 5%weight loss was 451.8 ^oC⁴94.7 ^oC,the corresponding temperature of10%weight loss was 500.6 ^oC⁵13.6 ^oC.It indicated that the molding powder has good thermal stability and thermal oxygen stability.High temperature drying made the solubility of molding powder worse and Tg increased,but the thermal stability decreased,and the conditions of thermo-compression film became more stringent.When the film was formed by thermo-compression for 0.5 h at 20 MPa and 250 ^oC,and the thermal properties of the film were basically the same as those of the molding powder.The amorphous state of the molding powder was determined by XRD.The fluorescence test results showed that the maximum emission wavelength was 460 nm at the excitation wavelength of 350 nm.A series of polyimide molding powders with conjugated structure were prepared by the reaction of benzeneguanoamine?BGA?and 2-?4-aminophenyl?-5-amino benzimidazole?PBIDA?with BPDA at different molar ratios,and their structure and properties were characterized.The results showed that the thermal stability of the molding powder became better and better with the addition of PBIDA.Under N₂,the carbon residue rate of the molding powder at 720 ^oC was 14.50%⁷2.10%,among which the carbon residue rate of the molding powder BGA-1 was 14.50%and that of molding powder BGA-0 was 72.10%.The corresponding temperature of 5%weight loss of molding powder was 332.9 ^oC⁵44.0^oC,and the corresponding temperature of 10%weight loss was 358.2 ^oC⁵89.4 ^oC.According to the maximum weight loss rate,the activity of amino group in monomer BGA is low,and it can only be partially reacted with BPDA.The conjugated triazine diamine monomer DBADPPT was reacted with?-BPDA,BPADA,BPDA,ODPA and BTDA,and the polyimide molding powder with different structure was prepared by using 4-phenylethinyl anhydride as sealing agent.The results showed that the molding powder had been iminated completely,and the Tg of the moulding powder was 216.80 ^oC²64.49 ^oC,Under N₂,the corresponding temperature of 5%weight loss was 479.2 ^oC⁴97.7 ^oC,the corresponding temperature of 10%weight loss was 503.5^oC⁵16.3 ^oC,the carbon residue rate at 800 ^oC was 55.48%⁶1.32%.Under the air,the corresponding temperature of 5%weight loss was 447.4 ^oC⁵02.9 ^oC,the corresponding temperature of 10%weight loss was 493.0 ^oC⁵16.3 ^oC.It indicated that the molding powder has good thermal stability and can be molded at 300 ^oC.The amorphous state of the molding powder was determined by XRD.The fluorescence test results showed that the maximum emission wavelength was 460 nm at the excitation wavelength of 350 nm except the molding powder PI-2-BPDA.It is expected to develop a blue fluorescent polyimide material.