Synthesis Of Hyperbranched Poly(Phenylene Sulfide)Via A Poly(Sulfonium Cation) Precursor

Poly(phenylene sulfide)(PPS), which is an excellent and engineering plastic, is inert to many chemicals, resists oxidation and shows striking thermal stability. However, many promising applications of poly(phenylene sulfide) as a functional material could be limited by its poor dissolvability in most common solvents due to its high crystallinity. The introduction of the tree-like structure skeleton would lead to form a multi-branched three-dimensional spherical framework with a large number of internal cavities, which made the polymer less entangled to reduce its crystallinity and improve the defects of poor solubility of linear poly(phenylene sulfide). The resultant polymer possessed excellent solubility in many common organic solvents. Its unique hyperbranched sulfur benzene conjugated structure showed special optical properties. Based on the regulating capability advantages of poly(sulfonium cation) as a precursor, we synthetized a series of PPS with different structures sand moleclar weights and carried out researches on their corresponding performance and fluorescence properties. The content of thesis consists of sevearal following parts:1. Synthesis of high molecular weight linear poly(phenylene sulfide) by oxidative polymerization via a soluble poly(sulfonium cation) precursorHigh molecular weight linear poly(phenylene sulfide) was efficiently synthesized via poly (sulfonium cation) through oxidative polymerization of methyl4-(phenylthio) phenyl sulfoxide. Polymerization proceeds in protic acid homogeneously. The poly(sulfonium cation) was soluble in common solvents such as formic acid and dimethyl sulfoxide. It was feasible to obtain high molecular weight poly(arylene sulfide) through the SN2reaction with pyridine as nucleophile. Tentative explorations of the structure and properties of linear poly(phenylene sulfide) were expected to be released by comparing with oxidative polymerization of diphenyl disulfide. The poly(sulfonium cation) was available as a soluble intermediate for the synthesis of high molecular weight poly(phenylene sulfide), which provides a reference for the synthesis of hyperbranched poly(phenylene sulfide).2. Properties of poly(phenylene sulfide) via a poly(sulfonium cation) precursorWe have succeeded in the synthesis of the high molecular weight hyperbranched poly(phenylene sulfide)(HPPS) via a soluble poly(arylsulfonium cation) precursor. Through the fumble and inquiry of different self-condensation of the sulfoxide monmer and polymerization conditions, we obtained a series of polymers with different molecular weights. Studies have showed that with increasing reaction time of self-polycondensation of the sulfoxide monomer, the color of the formed poly(arylsulfonium cation) was deeper and the molecular weight of the resulting polymer also increased. The resultant HPPS had excellent thermostability and solubility in many common organic solvents at room temperature such as toluene, dichloromethane, chloroform, acetonitrile, terrahydrofuran, N,N-dimethylformide, dimethyl sulfoxide and so on. The X-ray powder diffraction indicated that the presence of abundant branching would lead to substantial loss in crystallinity. UV-vis absorbance measurements were carried out at25℃in THF using various concentration ranges. Linear plots over the indicated concentration ranges, which conformed to the Beer-Lambert law, were an implication that the molecule exhibited favourable uniformity, failing to aggregate in organic solvent. Solvent polarity greatly affected the fluorescence properties of the polymer, the molecular weight had a significant impact on fluorescence emission intensity as well. The sample HPPS exhibited a significant "concentration selfquenching effect" and the quenching behavior of the fluorescence in HPPS quenched by Cu2+followed the static quenching equation:F0/F=1+KACQ The quenching efficiency was still as high as about25%at Cu2+concentration of about4×10-6g/mL. Different types of metal ions were provided with discrepant quenching effciency. Fluorescence quenching, which is a extremely sensitive analytical technique, may put into use of environmental monitoring so as to detect the presence of trace amounts of metal ions.