Synthesis And Characterization Of Novel Fluorinated Polyetherimides Containing Pyridine Groups In Main Chain

In this dissertation, the recent progress on the research of polyimides was investigated. The specific works contains three parts:1. The diphenolic compound, 4-(4-trifluoromethyl) phenyl-2,6- bis(4- phenol phenyl) pyridine(TPBHP) was successfully prepared from an Chichibabin reaction of4-hydroxy acetophenone and 4-trifluoromethyl benzaldehyde. The dinitro monomer,preparation of 4-( 4-trifluoromethyl phenyl)-2,6-bis [ 4-(4-nitro-3-trifluoromethyl phenoxy) phenyl ] pyridine(NTPPTPPPTB), was then obtained from the resulting diphenolic compound with 2-chloro-5-nitro-trifluorotoluene(CNBTF). The diamine monomer, preparation of 4-( 4- trifluoromethyl phenyl)- 2,6- bis [ 4-(4-aniline-3-trifluoromethyl phenoxy) phenyl]pyridine(ATPPTPPPTB), was synthesized by a nitro reduction of NTPPTPPPTB with hydrazine hydrate and Pd/C.The synthesis of polyetherimides(PEI) involved reacting the diamine(ATPPTPPPTB) and four different dianhydrides by polycondensation at low temperature conditions to yield poly(amic acid)s(PAAs) which were then cyclized into the final polyimides by heating. The PAA obtained displayed outstanding inherent viscosities ranging from 0.61 to 0.84 d L/g. All polyetherimides were thorough dissolved in dipolar organic solvents such as NMP, DMAc and also partly in a less polar solvents such as pyridine and THF. The series of PIs maintained that the glass transition temperatures of these PIs ranged from 280.3 °C to 314.7 °C and the decomposition temperature at 5 % 、 10 % weight loss ranged from 539.6 °C to561.9 °C and 579.1 °C to 593.9°C in nitrogen, respectively. Meanwhile, all the PIs left above 55.4 % residual even at 750 °C in nitrogen. Furthermore, the aromatic polyetherimide films exhibited moisture uptakes of 0.69-2.51%, and dielectric constants of 3.01-3.35 and optical transparency 73.252-74.706 % at λ= 800 nm. In addition, the PEI films exhibited mechanical properties with tensile strengths of74.77-100.62 MPa, elongations at break of 18.65-30.06 % and modulus of elasticity of 0.33-0.78 GPa.The elongation at break of PIc(30.06 %) is better, but the tensile strength is only 74.77 MPa, is not conducive to engineering materials, and PIa exhibited relatively ideal mechanical properties at the same time.2. A series of copoly(amic acid)s were achieved by a low temperature conditions copolycondensation of different ratio of ATPPTPPPTB/ODA with pyromellitic dianhydride(PMDA). And the intermediate PAAs were then converted to the final polyimides by heating.The poly(amic acid)s obtained displayed desirable inherentviscosities ranging from 0.58 to 0.98 d L/g. All copolyetherimides were almost dissolved in both dipolar organic solvents such as NMP, DMF and a less polar solvents such as Py and THF. The series of PIs maintained that onset decomposition temperature were above 500 °C and the 5 % 、10 % weight loss temperature ranged from 516.9 °C to 565.7 °C and 576.5 °C to 595.2 °C in nitrogen, respectively.Meanwhile, all the PIs left above 55 % residual even at 750 °C in nitrogen.Furthermore,the aromatic polyetherimide films exhibited moisture uptakes of0.54-2.27 %, and dielectric constants of 3.02-4.15 and optical transparency of69-86 % at λ= 700 nm. In addition, the PEI films exhibited mechanical properties with tensile strengths of 76.20-96.42 MPa, elongations at break of 14.03-55.34 % and modulus of elasticity of 0.76-1.66 GPa. Especial for PI4, whose tensile strength reached 96.42 MPa, the tensile modulus is 1.43 GPa, elongation at break up to25.54 %. It had a great improvement in contrast to the PI7 and almost can be used for engineering plastics.3. A series of copoly(amic acid)s were achieved by a low temperature conditions copolycondensation of different ratio of ATPPTPPPTB / BAPPPO with4,4-(hexafluoroiso propylidene)diphthalic anhydride(6FDA). And the intermediate PAAs were then converted to the final polyetherimides by a heating imidization route.The PAAs obtained displayed inherent viscosities ranging from 0.64 to 1.61 d L/g. The all polyetherimides were thorough dissolved in both dipolar solvents such as NMP,DMF and DMAc, and some a less efficient solvent such as THF and Py. The series of PIs maintained that the glass transition temperatures of these PIs ranged from 277.20 to 284.60 °C and the decomposition temperature at 5 % 、10 % weight loss ranged from 501.16 °C to 549.60 °C and 532.06 °C to 585.25°C in nitrogen, respectively.Meanwhile, all the PIs left above 50 % residual even at 760 °C in nitrogen.Furthermore, the polyetherimide films exhibited moisture uptakes of 1.33-2.84 %, In addition, the PEI films exhibited mechanical properties with tensile strengths of66.32-98.50 MPa, elongations at break of 6.90-16.28 % and modulus of elasticity of0.80-1.40 GPa. The tensile strength of PI6 reached 98.50 MPa, the tensile modulus was 1.14 GPa, Elongation at break up to 16.28 %. It had high mechanical strength and modulus and almost can be used for engineering materials.