Synthesis And Properties Of Hyperbranched Polyphenylene Sulfide And Metal Thiophenol Nanowires

Hyperbranched poly(phenylene sulfide)(HPPS)possesses the properties of linear poly(phenylene sulfide)(PPS)and good solubility in various organic solvents. HPPS is a rigid quasi-spherical molecule,thus it is suitable to be the rod block of a rod-coil copolymer that can possibly form special self-assembly morphology.The structure of HPPS can be changed via the reaction of-SH at the core terminal with other reactive group,further reaching to the improvement in the property of HPPS. This thesis describes the synthesis of HPPS and the modification of its core terminal as well the effect on the photofluorescent property.The preparation of copolymer PMMA-co-HPPS and its self-assembly behavior are discussed in detail.On other hand,the synthesis routes of metal aromatic sulfide nanofiber and its PVA composite are proposed.The content of thesis consists of several following parts:1.Synthesis and Photofluoreseenee of hyperbranehed poly(phenylene sulfide) (HPPS)HPPS was easily synthesized by the condensation reaction of potassium dichlorlbenzenthiol.The obtained noncrystalline HPPS has good solubility in THF, pyridine,and other organic solvents.HPPS possesses excellent thermal stability,with about 64%of polymer weight loss at 800℃.The maximum emission wavelength of HPPS in THF was about 460 nm.The quenching behavior by Cu²⁺well obeyed the Stern-Volmer equation:Fo/F=1+kC_Q,where F₀ and F is the fluorescence intensity at the reference condition free of quencher and with a quencher concentration of Cu²⁺, respectively,and k is a constant. 2.Synthesis and self-assembly behavior of linear PMMA extended hyperbranched poly(phenylene sulfide)(PMMA-co-HPPS)The PMMA-co-HPPS copolymer was synthesized by the chain transfer reaction via -SH group at core terminal of HPPS in a free radical polymerization process of methyl methacrylate(MMA).The self-assembly of PMMA-co-HPPS provides robust and inexpensive strategies for creating nanoscale materials,ranging from rods, ribbons,wires,vesicles,to beads,by changing the concentration of solvent.It was found that at higher concentration during the self-assembly process,rod-like or lamella micelles were formed;but at lower concentration the vesicles were obtained.3.Effect of core terminal structure on the fluorescent property of hyperbranched Poly(phenylene sulfide)In order to obtain HPPS with different terminal structure,the core terminal -SH groups of HPPS reacted with benzyl,phenyl,and naphthyl groups.The effects of three core structures(benzyl,phenyt,and naphthyl groups)on the fluorescent properties of HPPS with the comparison of the original HPPS.Phenyl and naphthyl groups might form conjugated structures with the HPPS backbones through sulfide bridges,leading to the increase in fluorescent intensity of HPPS.Whereas benzyl group has nearly no effect.Both the phenyl- and naphthyl-cored HPPS give rise to the peak at about 500 nm due to the formation of excimers.The naphthyl-cored HPPS' show drastic fluorescence enhancement that is 10-fold higher than the original HPPS.4.Preparation of aromatic metal sulfide nanofibersThe facile synthesis and characterization of novel metal(Cd^â…¡,Pb^â…¡or Ni^â…¡in this work)aromatic sulfide nanofibers with no template were reported.The aromatic metal sulfide nanofibers are expected to have the combined properties of both inorganic metal sulfides and organic polymers.They can emit very strong fluorescent light.The lead aromatic sulfide can be made with TiO₂ to get PN link,which emits light when the current through it.5.Preparation of metal aromatic sulfide nanofibers/PVA composite filmThe metal aromatic sulfide nanofibers/PVA composite film in PVA solution was synthesized.A series of PVA composite films with different nanofibers contents were prepared.When the content of nanofiber increased to 30%in the PVA film,the film becomes rubbery with reverse plasticizing performance.