反应性梯形聚氢基倍半硅氧烷合成方法的改进

对反应性梯形聚氢基倍半硅氧烷 (H T)的合成方法进行了改进 .首先利用硅羟基与硅氯基之间的脱氯化氢缩聚来代替以前采用的硅羟基间脱水缩聚反应 ,进一步提高了作为梯撑的对苯二胺之间氢键在聚合反应中的模板作用 .另外利用三甲基氯硅烷与对苯二胺梯撑的聚硅氧烷中间体的末端硅羟基进行封端反应 ,从而保证在脱除对苯二胺梯撑模板分子过程中避免进一步的无规缩合导致支化或交联 ,得到的反应性梯形聚氢基倍半硅氧烷 (H T)的规整性有所改善 .热分析结果表明与单链聚二甲基硅氧烷的Tg(- 12 3℃ )相比 ,其Tg 高达 117 0℃ ,证明这种梯形高分子具有刚性链结构 .尤其是2 9Si NMR谱中代表梯形主链上硅原子 (SiO3 2 )峰的基线宽度Δ =5 ,而采用硅羟基间脱水缩合方法得到聚合物的Δ =8～ 10 .表明该反应性梯形聚氢基倍半硅氧烷H T的规整性得到了明显的提高 .而且 ,该聚合物又是第一个可溶性、反应性、纯梯形主链无机高分子 ,它可以进一步通过硅 氢侧基接枝反应制备不同类型的梯形无机主链功能高分子 .     

两亲性笼型倍半硅氧烷（POSS）杂化高分子的自组装

笼型倍半硅氧烷（POSS）是一种由si-O-si键构成的高度对称笼型结构、端基具有极高的可设计性及高反应性新型有机一无机杂化材料,空间尺寸1～3nm;选取带有特定结构的光、电、磁等特性单元,利用活性聚合的方法可制得不同形状的POSS-Polymer杂化材料,通过溶剂、热、电、纳米印刷等方法“梳理”分子链结构,使之成为长程有序的纳米序列结构材料,获取具有预期结构和功能特性的高分子实体。本文从分子自组装的角度对两亲性笼型倍半硅氧烷（POSS）杂化高分子材料进行了介绍,分析了其在生物医药用高分子、智能高分子及低介电高分子材料等多个领域内的最新研究进展,并对今后的发展做了相关的预测与展望。     

侧基甲壳效应和甲壳型液晶高分子

侧链液晶高分子体系里,液晶基元可以通过尾接或腰接的方式与主链相连.一般认为,在液晶基元与主链间插入一段长度合适的＂柔性间隔基＂可有效实现主、侧链间的动力学去偶合,从而有利于侧基液晶基元之间的有序排列.作为一类特殊的腰接型侧链液晶高分子,甲壳型液晶高分子中体积较大的侧基（如棒状液晶基元）通过非常短的间隔基或仅通过一个碳-碳键直接横挂至主链上,这导致了强烈的甲壳效应,使得主链被迫伸展.因此,可从与＂柔性间隔基＂完全不同的角度出发,充分利用主链和侧基间的偶合作用,设计甲壳型液晶高分子.本文综述了腰接型侧链液晶高分子中的侧基甲壳效应、甲壳型液晶高分子中由主链与侧基相互作用所导致的特殊构象以及液晶相结构.研究表明,侧基甲壳效应在调控甲壳型液晶高分子的形状、尺寸以及螺旋结构等方面有重要作用.甲壳型液晶高分子可作为刚-柔嵌段共聚物的刚性链段,也可作为主/侧链结合型液晶高分子的主链部分参与到多层次分级超分子有序结构的构筑之中.     

具有重复单元的共轭分子的量子化学计算及其应用(上)

首先对题目作些说明。第一点说明是什么叫重复单元,高分子就是具有重复单元的,因为高分子是由单体聚合而生成,每个高分子都是由小分子的单体重复组成的。聚氯乙烯的重复单元就是—CHCICH_2—。当然不仅高分子有重复单元,小分子也有重复单元,例如:多烯烃的重复单元就是—CH—,所以具有重复单元的分子种类很多。另外,一个高分子除了重复单元之外,两头还有端基,例如离子型聚合,或者引发剂分子接到高分子的端基上。因此讨论具有重复单元分子的时候,一定要考虑两头的端基,端基可能有的简单,有的复杂;第二点要说明的是题目中指的是共轭分子,但是下面介绍的方法作为理论的本身不限于对共轭分子的处理,非共轭分子也可以用类似的方法     

共轭高分子聚[α,α′-二氰基对苯二亚甲基]的合成

<正> 共轭高分子具有耐热、耐辐射、半导性以及催化性能,可成为一种功能高分子材料。合成共轭高分子的方法很多。文献报道α-溴代苯乙腈经加热或与氨水作用可得到反式α,β-二苯基丁烯二腈。chanenor等人发现邻苯二乙腈的侧链溴化物不稳定,加热易脱溴化氢形成聚合物。本工作合成了α,α′-二溴代对苯二乙腈,通过脱溴化氢,得到共轭高     

若干杂环模型化合物的热氧化稳定性

<正> 自五十年代以来,耐热的杂环高分子取得了很多进展。曾报道聚酰亚胺、聚苯并咪唑、聚苯并噻唑、聚苯并噁唑、聚喹噁林及聚苯并噁嗪酮等都是性能较好的耐热高分子,而有些在工业上已得到应用。我们在进行芳杂环二腈聚合的工作中,曾将上述杂环结构引入二腈,以期获得性能优良的耐热高分子,所得结果已陆续报道。     

超分子构筑调控合成结构规整的梯形聚合物及其应用研究

综述了"超分子构筑调控的逐步偶联/聚合法",该方法将高分子化学与超分子化学相结合,利用多种类型的超分子弱键协同作用首先构筑预期的梯形超分子结构,再经聚合得到共价键梯形高分子.利用该方法合成了一系列结构规整的氧桥基和有机桥基梯形聚硅氧烷以及碳基梯形聚酯,并利用侧基间π-π叠加作用实现了对聚合物立体构型控制.扼要介绍了梯形聚合物在先进材料方面的应用,例如梯形聚硅氧烷液晶光致取向膜;由梯形聚硅氧烷合成的管状聚硅氧烷在高室温储存期微电子环氧塑封料方面的应用;以及基于梯形聚硅氧烷的拟筛板聚合物在二阶非线性光学材料方面的应用等.     

环基高分子缩聚体系的统计特征

针对由RBf型环形高分子和ABg型单体构成的环基高分子缩聚体系,从环基高分子的尺寸分布导出相应的高分子矩,进而给出环基高分子的数均分子量和重均分子量以及多分散指数等物理量.在此基础上,集中探讨了两类反应物的摩尔比、环形高分子的官能度及聚合度(分子量)对环基(环基链状和环基支化)高分子性质的影响.鉴于环形高分子对环基高分子相关特征的贡献可以发生主次转变,进而根据其数均分子量得到发生转变的反应程度.结果表明,环基高分子的多分散指数随着环形高分子官能度的增加而单调降低,但与反应物的摩尔比无关,而表征环形高分子贡献发生逆转的反应程度则与其官能度、聚合度及反应物的摩尔比密切相关.相关研究可为阐明环基高分子缩聚反应体系的统计特征提供有益的线索.     

壳聚糖膜固定化双水杨叉乙二胺合钴的合成与表征

具有可逆载氧活性的亚钴希夫碱配合物的合成、结构、电性质、磁性质及其它方面已进行了大量研究。由于这些配合物载氧后可使分子氧活化,它们作为工业催化剂的应用已成为一个重要的研究领域。阻碍过氧型载氧体和二聚体的形成是提高其载氧能力和催化活性的有效方法［１］。本研究将双水杨叉乙二胺合钻固定化于壳聚糖分子上,并对固定化产物进行了表征。旨在利用高分子固定化产物所表现的基位隔离效应得到１：１超氧型高分子固定化产物。１　实验部分１．１　仪器及试剂ＷＦＸ－ＩＦ２型原子吸收分光光度计;ＭａｔｔｓｏｎＦＴ－ＩＲ红外光谱…     

以Fréchet型树状分子为侧基的聚甲基硅氧烷的合成与表征

合成了一类新型的以Fréchet型聚芳醚树状分子为侧基的聚甲基硅氧烷高分子, 并对其进行了GPC, DSC, TGA, AFM, 荧光以及紫外可见光谱等方面的表征.     

Thermal‐crosslinked polyacrylonitrile fiber compacts

Polyacrylonitrile (PAN) textile fibers, in the form of fabrics or threads, were compacted in a heat‐pressure cycle and crosslinked by nitrile polymerization to form a thermoset composite article, whose mechanical properties were found to surpass those of commercially available polypropylene (PP) fiber counterparts. Additional advantages of the PAN compacts included their significant thermal stability (>300°C, i.e., twice that of PP) in addition to their flame retardancy, thereby rendering them as the structural material of choice for applications where heat protection and fire resistance are essential. Copyright © 2009 John Wiley & Sons, Ltd.     

Rapid electrothermal response and excellent flame retardancy of ethylene‐vinyl acetate electrothermal film

In this study, high electrical conductivity and flame retardant electrothermal ethylene‐vinyl acetate (EVA) films were fabricated by using carbon nanotubes‐wrapped ammonium polyphosphate (CAPP) and conductive carbon black (CCB). CAPP was used as a synergistic conductive filler and flame retardant to improve the electrical conductivity and fire safety of the electrothermal film at the same time. Besides, the heat release rate (HRR) and the total heat release (THR) of EVA‐5 decreased about 81.5% and 57.3% compared with those of pure EVA film, respectively. Moreover, by incorporating a small amount of CAPP, EVA‐5 can reach up to V‐0 rating with an limiting oxygen index (LOI) value of 31%. EVA film fabricated by CCB and CAPP as conductive material exhibited almost 10 times increment on electrical conductivity than that of same content for CCB alone. And time vs temperature profiles of EVA‐5 showed a stable trend over 3600 seconds without any offset at a given applied voltage of 15 V. Moreover, its excellent cycle heating performance indicated that the electrothermal film can be recycled, which meets the requirements of sustainable development. In a word, this novel strategy provides a simple and effective way to obtain a high conductive and fire safety electrothermal film.     

Determination of copper in urine by diffuse reflectance spectroscopy

A possibility of determining copper(II) after adsorption on polyacrylonitrile fiber filled with a KU-2 cation exchanger with immobilized 1-(2-pyridylazo)-2-naphthol (PANF–KU-2–PAN) is studied. The diffuse reflectance spectra of the carrier discs before and after the adsorption of copper in the batch mode are recorded. The dependences of the analytical signals of the copper complex on PANF–KU-2–PAN on adsorption conditions are studied. The conditions for determining 0.05–0.40 μg/mL of copper(II) by measuring diffuse reflection coefficient at 640 nm or visually by a color scale after the adsorption of copper from 20 mL of a solution containing 0.01 M of HCl are found. The determination of 0.1 μg/mL of copper does not interfered with equal amounts of Co, Zn, and Pb and double amounts of Ag, Fe(III), Cd, Mn(II), Bi(III), and Cr(III). The procedure is used for urine analysis. The following conditions of the preparation of urine samples for the determination of copper were selected: boiling with hydrogen peroxide followed by acidification to pH 2. A procedure for determining copper in urine with a limit of detection of 0.03 μg/mL was developed; the relative standard deviation does not exceed 25%; the duration of analysis of 5–6 samples is 30–35 min.     

Evolution of the composition and structure of PAN carbon fiber during preoxidation

Using scanning electronic microscope, X-ray diffraction analysis, PYR-GCMS and IR etc., we studied the evolving process of the composition and structure of PAN carbon fiber during preoxidation. In the initial stage of preoxidation, PAN filament tows disappear and become semi-thaw. At first, reactions happen between the copolymers and esters disappear. The molecules annularly crosslink and the index of cyclation slowly increases. It is easy to fix the structure and form defects during the initial and the medium stages, which are most reactive. More traction is advised in these stages to minimize the structural deficiencies. In the medium stage of preoxidation, the fiber was reshaped into new sheet stacks and gradually changed to sheet sectors, and this structure tends to be stable in the final stage. Induced by acid and ester copolymer, PAN fiber forms a very stable cycle structure in the final stage. Besides, monomer, dimmer and trimer obviously decrease. In the final stage of the preoxidation, there exi     

Thermal behavior of polyacrylonitrile polymers synthesized under different conditions and comonomer compositions

Polyacrylonitrile (PAN) polymers are used as precursors for carbon fiber production. This process requires an oxidative stabilization step, which can be studied by differential scanning calorimetry (DSC). In this sense, thermal behavior of PAN based terpolymers by different polymerization processes, compositions and itaconic acid concentrations in the reaction media were investigated. The obtained results showed that the addition of itaconic acid and methyl acrylate as comonomers resulted a lower heat flow during the process comparing to the PAN homopolymer. It suggested that these comonomers aid the oxidative stabilization stage for all studied process. The redox system polymerization at 40°C resulted in a lower heat flow. Itaconic acid decreases slightly initial and peak temperatures of the terpolymer and heat flow until concentration of 3y. The cyclization temperature decreases when MAis incorporated into the terpolymer compared to the MMA terpolymer and increases when MAA is the acidic monomer. Among terpolymers the AN/MA/AA polymer showed the best thermal behavior for carbon fiber producing.     

聚丙烯腈高分子半导体纤维的研究——聚丙烯腈高分子半导纤维的制备及其半导体特性

经四氯化锡处理的聚丙烯腈纤维,在进一步热处理过程中可以成为一种高分子半导纤维。它具有如下四个特点:1.纤维电阻率在10~3—10~(12)欧姆·厘米范围内可以控制热处理温度而随意调节。2.水解处理干燥后纤维的电阻值基本不变。3.有足够的机械强度可以进行多种形式的加工。4.纤维的电阻-温度、电导率-频率依赖关系,直流伏-安特性的试验结果表明它具有有机半导体特性,是一种兼有良好电性能和力学性能的高分子半导纤维。     

Electrical resistance and heat generation of polypyrrole‐coated polyacrylonitrile nanofibrous and regular fibrous mats

This article reports the effect of fiber diameter on the electrical resistance and heat generation of fibrous polyacrylonitrile (PAN) mats coated with polypyrrole during chemical in situ polymerization. Polypyrrole is one of the important intrinsically conducting polymers that perform similar to semiconductors. The electrical resistance of polypyrrole‐coated mats depends on the fiber diameter, the applied pressure on the surface of the mats, and the mat thickness. The electrical resistance of polypyrrole‐coated PAN fibrous mats decreases as fiber diameter decreases. Moreover, electrical resistance decreases considerably as the mat thickness as well as the applied pressure on it increases. It was also observed that the heat generated in polypyrrole‐coated PAN fibrous mats increases with voltage and duration of the applied voltage. Lower fiber diameter also leads to higher heat generation. Furthermore, electrical current increases rapidly in the initial stages of applying voltage and then shows a marginal increase. Considering their high specific surface area, nanofibers convey considerable improvement in the electrical conductivity as well as heat generation capacity of the mats made from them. Copyright © 2011 John Wiley & Sons, Ltd.     

Viscometric measurement of the thermodynamics of PAN terpolymer/DMSO/water system and effect of fiber‐forming conditions on the morphology of PAN precursor

The thermodynamics of polyacrylonitrile (PAN) terpolymer/dimethyl sulphoxide (DMSO)/water system was investigated by viscometric method. Fourier transform infrared (FTIR) measurement of the temperature dependence of polymer/solvent interaction was performed in the range of 25–80 °C, which was in good agreement with viscometric results. Meanwhile, the upper critical solution temperature (UCST) for PAN terpolymer/DMSO/water system, which is proved to be stable one, was determined from the temperature dependence of the expansion factor α_η 3 . The morphology of PAN precursor prepared by dry‐jet‐wet spinning with different fiber‐forming conditions was examined with a scanning electron microscope (SEM). Judging from SEM photographs, not only the number and size of microvoids of PAN precursor gradually increase, with increasing the temperature of coagulation bath, but also the cross‐section shape of PAN precursor changes from nephroid shape to elliptical shape or circular shape. Therefore, PAN precursor with different microstructures can be fabricated at different quenching‐depths, suggesting that the final microstructure of the PAN precursor greatly depends on the phase separation in the fiber‐forming process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1997–2011, 2008     

Ethylene propylene diene monomer rubber‐based heat shielding materials for solid rocket motor: Impact of Kevlar fiber reinforcement on the thermal and mechanical properties

This work scrutinizes the utilization of ethylene propylene diene monomer rubber matrix (EPDM) with an embodiment of aramid fiber for the heat shielding applications in solid rocket motor (SRM). Aramid fibers are aromatic poly‐paraphenylene terephthalamide, here deployed are Kevlar fibers (KF). However, the literature that encompasses the thermal and mechanical behavior with the fiber loading is reported nowhere else. The effect of fiber addition on the surface morphology and density was thoroughly studied, and it revealed that the EHSMs were of lower density to act as an efficient payload for the SRM. In this regard, the thermal conductivity, heat capacity, thermal diffusivity, fire behavior, and mechanical properties of the EPDM/KF‐based EHSMs were explored. The results revealed that the EHSMs are thermally insulating and thermally stable material with balanced mechanical properties that can engender the thermal and mechanical strains of the rocket motor. Furthermore, other analytical techniques such as scanning electron microscopy and energy dispersive X‐ray spectroscopy have been exploited to monitor the performance of the char residues of the EHSM to delineate its performance in the fire atmosphere.     

阻燃剂及材料的阻燃处理

阻燃剂是能够保护材料不着火或使火焰难以蔓延的化学物质。介绍了常见阻燃剂的种类、阻燃机理、材料的阻燃处理及新型阻燃剂的发展,以增强人们对阻燃技术领域的认识和了解。