The Design And Synthesis Of Diamine Monomer Containing Three Fused Ring And Its Application In Polyimide

In recent years,polyimide(PI)has attracted more and more attention in the field of flexible Organic Light-Emitting Diode(FOLED)package due to its outstanding thermal performance and comprehensive performance.But poor barrier performance of polyimide limiting its application in FOLED packaging field.However,designability of the molecular structure of the polyimide offers a tremendous potential for improving the barrier performance.In this paper,through reasonable molecular design,a series diamine containing three fused ring structure(carbazole,fluorenone,dibenzofuran or dibenzothiophene)and having rigid planar features were synthesized.A series polyimide contain rigid planar structure in the main chain were prepared by the reaction of equal molar amounts of the resulting diamine with commercially available dianhydride PMDA.Planar structure can improve packing density of polyimide molecular chain,reduce free volume of the polymer,effectively improve the barrier properties of polyimide;rigid structure can improve rigidity of polyimide molecular chain,reduce motility of the molecular chain,limit the permeability,effective improve the barrier properties of polyimide,and rigid structure can effectively improve the thermal stability and mechanical properties of the polyimide.The structures and properties were characterized by means of characterization such as nuclear magnetic resonance(NMR),mass spectrometry(MS),infrared spectroscopy(FT-IR),elemental analysis(EA),thermal gravimetric analysis(TG)and differential scanning calorimetry(DSC).The properties of the polyimide films were characterized by gel permeation chromatography(GPC),infrared spectroscopy(FT-IR),thermal gravimetric analysis(TG),differential scanning calorimetry(DSC),dynamic mechanical analysis(DMA),thermal mechanical analysis(TMA),atomic force microscope(AFM),X-raydiffraction(XRD),positron annihilation instrument,oxygen permeability instrument and moisture vapor permeability instrument.Themain contents and conclusions are summarized as follows:(1)Combined the different three fused ring structure moieties,3,6-CPDA?DFPDA and DTPDA were synthesized.Films of 3,6-CPPI?DFPPI and DTPPI were synthesized from the resulting diamine monomer3,6-CPDA?DFPDA and DTPDA with PMDA.The results indicate that such PI films are semi-crystalline polymers.It has excellent thermal properties,low surface roughness,good barrier properties,flexibility and mechanical properties.Their decomposition temperatures(at 5% weight loss)in the range of 558 ~ 583 ?,10% weight loss temperature in the range of 587 ~ 609 ?;Tgs in the range of 427 ~ 440 ?;coefficient of thermal expansion(50 ~ 200 ?)in the range of 25.85 ~ 39.11 ?m/m·?;water vapor permeability coefficient in the range of 55.358 ~ 81.084gm-mil/[m~2-day],oxygen permeability coefficient in the range of 57.357~ 84.954 cc-mil/[m~2-day].Compared to traditional polyimide film(Kapton),barrier properties of novel polyimide increased by 50%.In three PI films,overall performance of 3,6-CPPI is best.Chain of3,6-CPPI have good planarity.It is conducive to increasing packing density of polymer chain.In the meantime,3,6-CPPI would have hydrogen bonds by introducing carbazole moiety.(2)Combined the 2,7-position of carbazole structure moieties,2,7-CPDA and M-2,7-CPDA were synthesized.Polyimide films 2,7-CPPI and M-2,7-CPPI were synthesized from the resulting diamine monomer2,7-CPDA and M-2,7-CPDA with PMDA.Compare 3,6-CPPI,since the2,7-substituted is conducive to the closely packed of polyimide chain,the barrier properties of 2,7-CPPI is far superior to 3,6-CPPI,wherein,oxygen permeability and water vapor permeability coefficient of2,7-CPPI is as low as 0.503 cc-mil/[m~2-day] and 0.286 gm-mil/[m~2-day];compare 3,6-CPPI,barrier properties of 2,7-CPPI increased by two orders of magnitude;2,7-CPPI and M-2,7-CPPI have excellent thermal properties,Tgs is greater than 400 ?;T5 % is 581 ? and 563 ?,respectively;coefficient of thermal expansion(50 ~ 200 ?)is 2.897 and28.97 ?m/m· ?,respectively.It has low surface roughness and good mechanical properties,in which,tensile strength 2,7-CPPI reached 143.8MPa.(3)Based on previous research foundation,methyl be introduced into carbazole of 2,7-CPDA,9-M-2,7-CPDA was synthesized;combined the 2,7-position of fluorenone,FOPDA also was synthesized.Polyimide films 9-M-2,7-CPPI and FOPPI were synthesized from the resulting diamine monomer 9-M-2,7-CPDA and FOPDA with PMDA and research effect of inter molecular forces on the barrier properties of the polyimide.The results showed that 9-M-2,7-CPPI and FOPPI have weakening intermolecular forces.It leads to crystallinity of the polyimide decline.Weakening intermolecular force and low crystallinity together lead to barrier properties of polyimide decreased by one orders of magnitude.Oxygen permeability coefficients of 9-M-2,7-CPPI and FOPPI are 9.505 and 20.583 cc-mil/[m~2-day],water vapor permeability coefficient are10.235 and 8.748 gm-mil/[m~2-day].But 9-M-2,7-CPPI and FOPPI remains good thermal stability,T5 % of which are 536 ? and 586 ?,respectively;thermal expansion coefficient are 8.415 and 1.282 ?m/m·?,respectively.(4)Combined the carbazole moieties,3,6-CDA were synthesized.Polyimide films 3,6-CPI were synthesized from the resulting diamine monomer 3,6-CDA with PMDA.Because its rigid structure is smaller than 3,6-CPPI?s,thermal properties of 3,6-CPI is slightly worse than the3,6-CPPI.Tgs of 3,6-CPI above 397 ?,T5 % above 559 ?.Compare carbazole unit,large rigid planar structure containing a carbazole and two benzene ring is not conducive closely packed of polymer segment.Thus,compared to the 3,6-CPPI,the barrier properties of 3,6-CPI increased by100%,the oxygen permeability and water vapor permeability coefficient of 3,6-CPI are as low as 23.432 cc-mil/[m~2-day],and 29.157gm-mil/[m~2-day].