Study On Novel Poly(Arylene Ether Nitrile)s Containing Phthalazinone Moieties

Poly(arylene ether nitrile)s has been noted as a kind of important polymeric material which present a combination of outstanding properties such as high thermal stability, good chemical resistance and excellent mechanical properties. However, the commercial poly(arylene ether nitrile)s was crystalline polymer with poor solubility in most organic solvents at room temperature, which resulted in difficulty for application in the insulating coating and separative membrane etc. In this work, our efforts had been focused on synthesis of poly(arylene ether nitrile)s with good solubility and high thermal properties by the introduction of twisted, noncoplanar phthalazinone moieties into poly(arylene ether nitrile)s backbone.In this thesis, the twist and noncoplanar phthalazinone moieties had been successfully introduced into poly(arylene ether nitrile)s by the nucelophilic reaction of the bisphenol-like monomer, 4-(4-hydroxyphenyl)-phthlazin-1(2H)-one (DHPZ) and 2,6-difluorobenzonitrile (DFBN) firstly. The synthesis process was optimized. After the optimization of the polymerization, the inherent viscosity of this polymer could reach 1.02 dL/g. The poly(phthalazinone ether nitrile)s (PPEN) showed amorphous nature as determined by wide angle X-ray diffraction (WAXD) and was soluble in a variety of aprotic polar solvents, such as N-methyl-2-pyrrolidinone (NMP), N, N-dimethylacetamide (DMAc), chloroform etc. The PPEN exhibited outstanding thermal properties with glass transition temperature (T_g) of 295℃and 10% loss temperature (T_10%) of 527℃in nitrogen atmosphere.In order to reduce the cost, 2,6-dichlorobenzonitrile(DCBN) had been used to replace DFBN. But we couldn't obtain high molecular weight because of DCBN's lower reactivity.With the help of the molecular design, the bisphenol-like monomer DHPZ's reactivity was increased by the incorporation of electron-donating group. Three substituted PPENs were synthesized by the substituted bisphenol-like monomer and DCBN. All polymers showed good solubility in polar solvents such as NMP, DMAc, chloroform etc. The structures of these PPENs were confirmed by FT-IR and ¹H NMR techniques. The thermal properties, crystalline properties were characterized through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and WAXD. All polymers exhibited lower thermal properties compared with the unsubstituted PPEN, and the lowest Tg of these copolymers was 277℃, the lowest T_10% was 451℃in N₂ atmosphere. Aim to prepare high molecular weight PPEN from DHPZ and DCBN, utilized potassium fluoride (KF) as the cocatalyst of the polymerization system. K₂CO₃ and KF were added in the polymerization system of DHPZ and DCBN together. The fluoridation and nucleophilic replacement polymerization had carried in the same reaction system. The high molecular weight PPEN was obtained by the optimization of the reaction conditions. The inherent viscosity of this polymer could reach 0.90dL/g. The utilization of KF as cocatalyst could obviously reduce the cost.The high reactivity third monomer such as 4,4'-difluoro benzophenone(DFK),4,4'-dichloro diphenyl sulfone(DCS) and bis(4-fluorobenzoyl)-benzene (DFKK) had been used to synthesize the PPEN copolymers. PPENK, PPENS, and PPENKK had been successfully prepared. The thermal properties, solubilities, electronical properties and crystalline properties of copolymers were characterized. New copoly(arylene ether nitrile)s had good thermal properties and solubility. T_g of these copolymers ranged from 252 to 323℃, T_10% ranged from 449 to 541℃in nitrogen atmosphere. All polymers showed good solubility in polar solvents. The polymers' properties could be controlled by the structure adjustment.The high reactivity and cheap third monomer such as hydroquinone (HQ) and 2, 2-bis (4-hydroxyphenyl)-propane (BPA) had been used to partilly replaced DHPZ to synthesize the PPEN copolymers. Two series of PPENs copolymers including PPEN-HQ and PPEN-BPA had been synthesized. The polymers' thermal properties, solubilities, electronical properties and crystalline properties had been studied. The results showed that the introduction of HQ and BPA could increase the polymers' inherent viscosities with the little decrease of the thermal properties. T_g of these copolymers ranged from 200 to 277℃, T_10% ranged from 449 to 517℃in nitrogen atmosphere. All polymers showed good solubility in polar solvents. We could reduce the cost by the copolymerization.The application of poly(phthalazinone ether nitrile ketone)s in insulating varnish was reported. The insulating varnish prepared from PPENKs had excellent mechanical properties electro-insulating properties and thermal properties. The adhesion of the coatings was 1 grade and pencil hardness was 6H. The surface resistance coefficients and volume resistance coefficients were 10¹³Î©and 10¹⁶Ω·cm respectively. The minimum scrape forces were larger than 9.1 N. The breakdown voltages was larger than 6800 V (25℃). The thermal shock temperatures was larger than 400℃. Both insulting coatings and enamel wires showed good stability in strong acid, strong base and salt solutions.