超支化聚苯硫醚与金属苯硫酚纳米线的合成及其性能研究

【作者】 许让磊；

【导师】 施文芳； 刘和文；

【作者基本信息】 中国科学技术大学 ， 高分子化学， 2008， 博士

【摘要】 超支化聚苯硫醚（HPPS）是一种具有三维立体结构的刚性分子,极易溶解于多种有机溶剂。HPPS可以作为自组装体中rod-coil二嵌段共聚物中的刚性嵌段;同时,由于合成过程中空间位阻效应,HPPS具有未反应的端巯基,因此可以通过巯基的反应改变HPPS核端基团的结构,从而改变HPPS的性能。本论文论述了HPPS的合成及其核端基的改性对于二发光性能的影响;以及共聚物PMMA-co-HPPS的自组装行为;另外,对于金属芳基硫化物纳米纤维及其PVA复合材料进行了初步探索。具体研究内容分为以下几个部分:1、超支化聚苯硫醚的合成及其荧光性能通过AB₂单体2,4-二氯苯硫酚钾的热缩合反应合成了超支化聚苯硫醚（HPPS）。高度支化的HPPS为非晶态,极易溶于四氢呋喃、吡啶和其他有机溶剂。HPPS具有非常优异的热稳定性,800℃时的热失重仅40%左右;最大发射波长为460 nm。用Cu²⁺作为淬灭剂检测的其淬灭行为,遵守斯特恩-沃尔默方程:F₀/F=1+kC_Q,其中F₀和F分别为参比环境下无淬灭剂时和淬灭剂为C_Q时的荧光强度,k为常数。2、共聚物PMMA-co-HPPS的合成及其自组装行为通过HPPS端巯基链转移方法合成了线形-树形PMMA-co-HPPS共聚物,通过改变溶剂的浓度,可以获得包括棒、带、线、囊泡和小球形状的多种纳米自组装体。当聚合物浓度较大时,形成棒状和带状胶束;当浓度较小时,则形成了囊泡。3、核端结构对超支化聚苯硫醚荧光性能的影响将HPPS核端巯基分别接枝苯基、苯甲基和萘基,比较它们的的荧光性能,发现苯基和萘基可以通过硫桥键与HPPS形成共轭结构,使聚合物荧光强度增强,而苯甲基基团却对HPPS的荧光性能基本没有影响。苯基和萘基封端的HPPS在溶液中均形成了激基缔合物,从而产生了500nm处的荧光发射峰。萘封端的HPPS的荧光强度相比HPPS高十倍以上。4、金属芳香基硫化物纳米纤维的制备合成了金属（铅、镉和镍）芳基硫化物纳米纤维,兼有无机金属硫化物和有机聚合物的性能。研究发现,铅和镉的芳基硫化物发出比较强的荧光;芳基硫化铅可与TiO₂构成PN结,可以发出比较稳定的脉冲光束。5、金属芳基硫化物纳米纤维/PVA复合材料膜的制备在PVA溶液中合成了一系列不同含量的金属芳基硫化物纳米纤维/PVA复合材料。研究发现,纳米纤维呈规整棒状,而且其含量增加到30%时,PVA复合膜以弹性体形态存在,具有反向增塑性能。更多还原

【Abstract】 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^Ⅱ,Pb^Ⅱor Ni^Ⅱin 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.更多还原