Studies On Design, Synthesis And Properties Of Novel Polyarylates Containing Phthalazinone Moieties

Polyarylates have been known as one of high performance polymers, and have been widely applied in the aviation, automobile, electronic and mechanical industries because of their good thermal stabilities and mechanical properties. However, most polyarylates obtained commercially encounter processing difficulty owing to their high glass transition or melting temperature coupled with insolubility in common organic solvents and this restricts their application in the insulating coating and separative membrane etc. In this work, our efforts have been focused on synthesis of polyarylates with good solubility without sacrificing thermal properties by the introduction of twisted, noncoplanar phthalazinone moieties into polyarylates backbone. This work is financially supported by the national high technology and development program of China (NO.2003AA33G030).In this thesis, the reaction activity of the two active hydrogen atoms O-H and N-H of the bisphenol-like monomer, 4-(4-hydroxyphenyl)-phthlazin-1(2H)-one (DHPZ) was investigated firstly. The results showed that the only hydrogen atom O-H of bisphenol-like monomer DHPZ ccould react with benzoyl chloride. Secondly, the dinitrile compound 4-[4-(4-cyanophenoxyl) phenyl]-2-(4-cyanophenyl) phthalazin-1-one (H-DN) was prepared by the nucleophilic chlorodisplacement reaction of DHPZ and p-chlorobenzonitrile. The intermediate dinitrile H-DN was converted into 4-[4-(4-carboxyphenoxyl) phenyl]-2-(4-carboxyphenyl) phthalazin-1-one (H-DA) by alkaline hydrolysis. Moreover, the synthesis and refining of H-DN was optimized to increase the yield of the diacid containing phthalazinone moiety H-DA and the structures of compounds H-DN and H-DA were characterized by FTIR, NMR, MS, HPLC techniques.A series of novel polyarylates containing phthalazinone moieties were synthesized from the diacids containing phthalazinone moiety H-DA, 4-[3-chloro-4-(4-carboxyphenoxyl)phenyl]-2-(4-carboxyphenyl) phthalazin-1-one (oCI-DA), 4-[3-methyl-4-(4-carboxylphenoxy)phenyl]-2-(4-carboxyphenyl) phthalazin-1-one (oM-DA), 4-[3, 5-dimethyl-4-(4-carboxylphenoxy)phenyl]-2-(4-carboxyphenyl) phthalazin-1-one (oDM-DA), 4-[2-methyl-4-(4-carboxylphenoxy)phenyl]-2-(4-carboxyphenyl) phthalazin-1-one (mM-DA) with various bisphenols by direct solution polycondensation. The synthetic polyarylates had high molecular weight. The structures of these polyarylates were confirmed by FT-IR and ~1H NMR techniques. The thermal properties, crystalline property of polyarylates were characterized through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), differential thermogravimetry (DTG) and wide angle X-raydiffraction (WAXD). All polymers exhibited excellent thermal properties, and the glass transition temperatures (Tg) of these polyarylates ranged from 207 to 292 °C, the degradation temperatures (r10) ranged from 417 to 481 °C in nitrogen atmosphere, among these polyarylates, polyarylate PARlb derived from aromatic diacid H-DA and hydroquinone showed the highest Jio value, indicating higher thermal stability than ther other polyarylates. All polymers showed good solubility in polar solvents such as iV-methyl-2-pyrrolidinone (NMP), N, iV-dimethylacetamide (DMAc), pyridine (Py) efc.Transparent and flexible films could be cast from their NMP solutions. Moreover, the substituent groups on phthalazinone moieties could slightly decrease the thermal properties of the polyarylates and increase the solubility of the polyarylates.A copolyarylate containing phthalazinone moieties and ether linkages prepared from equal molar ratio of H-DA, terephthalic acid (TPA) and 2, 2-bis (4-hydroxyphenyl)-propane (BPA) by direct solution polycondensation was used to find out an optimum reaction condition. With a series of experiments, all the factors (such as the molar of benzenesulfonyl chloride, N, iV-dimethyl-formamide, reaction temperature, addition method of BPA and reaction time) which might affect the polycondensation were investigated to find out an optimum reaction condition for the preparation of high molecular weight polyarylates. New two copolyarylates with high inherent viscositiy were prepared from BPA and mixed aromatic diacids of TPA/H-DA or TPA/oDM-DA. New copolyarylates had good thermal properties, solubility and mechanical performance, which was of potential as low cost resins with high performance.Other new copolyarylates were also prepared from 4,4'-thiodiphenol and mixed diacids of TPA/ H-DA or TPA/oDM-DA. The copolyarylates exhibited excellent thermal properties and good solubility, and the solubility of copolyarylates decreased with the increasing of the TPA content. The solubility of these copolyarylates decreased in comparison with the copolyarylates containing isopropylidene.The application of polyarylates containing phthalazinone moieties in insulating varnish was reported for the first time. The mechanical properties of insulating varnish prepared from the polyarylates PARI containing phthalazinone moieties were investigated. Insulating varnish of these polyarylates had excellent mechanical properties and low water absorption. The insulating varnish prepared from polyarylates PARld~PAR5d had excellent mechanical properties and thermal properties, and the effect of substituent group on the thermal shock temperatures of these polyarylates enamel wires were also investigated. The enamel wires of polyarylates PARla, PARlc and PARld had excellent mechanical properties, thermal properties, good electrical insulation and corrosion resistance.