Synthesis And Characterization Of Polyamides Derived From4-(4-Trilfuoromethylphenyl)-2,6-bis(4-aminophenyl) Pyridine

In this dissertation, the recent progress on the research of aromatic polyamideswas investigated. The main skeleton of this dissertation contains three parts:1. A pyridine-containing aromatic dinitro compound4-(4-triflouromethylpheny)l-2,6-bis(4-nitrophenyl)pyridine (MPNPP) was synthesized via amodified Chichibabin reaction from4-trifluoromethylbenzaldehyde and4-nitroacetophenone. Then a diamine monomer,4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine(MPAPP)was obtained by catalytic hydrogenation of thedinitro compound (MPNPP) using hydrazine hydrate and Pd/C catalyst under thecondition of70–80oC.2. The fluorinated polyamides containing pyridine and sulfone moieties wereprepared from the diamine monomer by the low temperature polycondensation withfour kinds of sulfone moieties based dibenzoyl chlorides. The novel aromaticpolyamides were amorphous with inherent viscosities of0.70–1.06dL/g, and readilysoluble in not only dipolar aprotic solvents such as N-methyl-2-pyrrolidinone (NMP),N, N-dimethylacetamide(DMAc), N, N-dimethylformamide(DMF), but also in non-polar solvents such as pyridine and tetrahydrofuran at room temperature, whichshowed all the polymers with excellent solubility in organic solvents. The resultingpolymers showed glass transition temperatures between280–318oC and10%weightloss temperatures ranging from485°C to516°C, and char yields at800°C higherthan50%in nitrogen. All polymers could be cast into transparent, flexible and strongfilms from DMAc solutions with good mechanical properties with tensile strengths of72–81MPa, elongations at break of12–15%, and tensile moduli of1.8–2.1GPa.These polymers had low dielectric constants of3.40–3.51(1000Hz), low moistureabsorption in the range of1.08–1.28%, and high transparency with anultraviolet–visible absorption cut-off wavelength in the374–382nm range.3. A series of novel fluorinatede copolyamides containing pyridine moieties withhigh molecular weight were synthesized from the diamine monomer(MPAPP),different ratio of terephthalyl chloride (TPC) and isophthaloyldichloride (IPC) by low temperature solution polycondensation with the condition of pyridine. All thecopolyamide are amorphous with inherent viscosities of0.38–0.78dL/g, and readilysoluble in dipolar aprotic solvents such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide(DMAc), dimethyl sulfoxide(DMSO) at room temperature. Theresulting polymers showed glass transition temperatures between334–568oC and5%weight loss temperatures ranging from314to526oC,5%weight loss temperaturesranging from334–568oC, and char yields at800°C higher than24%in nitrogen.Meanwhile, these fluorinatede copolyamides containing pyridine moieties showedexcellent mechanical properties with tensile strengths of33.6867.88MPa, elongationsat break of6.6646.23%, and tensile moduli of1.322.09GPa. And these polymershad low moisture absorption in the range of1.65–2.22%, and high transparency withan ultraviolet–visible absorption cut-off wavelength in the392–401nm range. At last,through comprehensive analysis and comparison, when the ratio of TPC and IPC was60/40, various properties of resulting copolymer was the best, namely the ratio was60/40with optimum conditions.