Synthesis of Chain-End Functionalized PP and Applications in Exfoliated PP/Clay Nanocomposites

This paper summarizes our research to the preparation of chain-end functionalized isotactic polypropylene (i-PP) having a terminal functional group, such as an OH and an NH₂. The chemistry involves metallocene-mediated propylene polymerization using the rac-Me₂Si[2-Me-4-Ph(Ind)]₂ZrCl₂/MAO complex in the presence of styrene derivatives (St-f) and hydrogen, which serve as the chain transfer agents. The molecular weight of the resulting i-PP polymers with terminal OH or NH₂ groups (i.e., PP-t-OH and PP-t-NH₂) are inversely proportional to the molar ratio of [St-f]/[propylene]. Despite the extremely low concentration of functional groups, the high molecular weight NH₃⁺-terminated PP (PP-t-NH₃⁺) exhibits a distinctive advantage over other functional PP polymers containing side chain functional groups or long functional blocks. The terminal hydrophilic NH₃⁺ cation, with good mobility and reactivity, effectively ion-exchanges the cations (Li⁺, Na⁺, etc.) located between the clay interlayers, and anchors the PP chain to the clay surfaces. On the other hand, the remaining rest of the unperturbed, end-tethered, high molecular weight PP tail exfoliates the clay layers. This exfoliated structure is maintained even after further mixing of the PP-bearing platelets with pure, neat PP polymers.     

粘土/聚烯烃纳米复合材料研究进展

原位聚合;插层复合;粘土/聚烯烃纳米复合材料研究进展     

聚酰胺/粘土纳米复合材料

聚酰胺／粘土纳米复合材料是一种新型的有机－无机纳米复合材料。在无机物含量远少于常规填充复合材料的情况下就可以具有较好的力学性能、阻隔性能等,热稳定性能也显著提高,并具有阻燃性和各向异性。是一种性能优异的、具有广泛应用前途的纳米复合材料。综述了该纳米复合材料的制备、性能和应用前景等。     

聚酰胺/粘土纳米复合材料的制备、结构表征及性能研究

聚酰胺／粘土纳米复合材料，由于粘土以纳米尺度均匀地分散在聚酰胺基体中以及粘土与基体间强的化学结合，较常规填充增强聚酰胺复合材料具有更高强度、模量、耐热、气体阻隔等性能，是一种性能优异的聚酰胺材料。本文重点综述了该混杂材料的制备、结构表征、特殊的界面相互作用、力学性能、结晶行为及结晶动力学等方面的研究，并展望该材料的应用前景。     

MEH-PPV/层状硅酸盐纳米复合物的光物理性质

用稳态和时间分辨荧光光谱技术,结合13C固体NMR研究了共轭高分子聚2-甲氧基-5-(2′-乙基-己氧基)-1,4-亚苯基亚乙烯基(MEH-PPV)在层状硅酸盐(montmorillonite,MMT)纳米片层受限空间中的聚集态结构、性质和对外场的响应特性.结果表明,MMT二维纳米受限空间对MEH-PPV自聚集的阻隔作用,减少了MEH-PPV链间近程相互作用较强的H-聚集,增加了J-聚集含量.结果激发态激子自淬灭的几率降低,稳态荧光量子产率提高和动态荧光寿命的延长;通过共轭碳原子的自旋-晶格弛豫时间的测定,观察了MMT对聚合物分子运动的影响,并由此探讨了MEH-PPV凝聚态与光物理性质的关系.     

短链分子交换粘土纳米级复合材料合成和表征

短链分子交换粘土纳米级复合材料合成和表征石恒真＊ＬａｎＴｉｅＰｉｎｎａｖａｉａＴ．Ｊ．（河南周口师范高等专科学校化学系周口４６６０００）（美国密执安州立大学化学系）关键词嵌入，粘土，纳米级复合材料，合成，表征１９９６－０６－０７收稿，１９９６－１２－...     

Design,Synthesis and Characterization of 3,4-Dihydro-2H-pyran Containing Copolymer/Clay Nanocomposites

We introduce briefly surface modification of clay minerals, structure, properties and, characterization techniques of polymer-clay (PCN's) nanocomposites. Organically modified layered-silicates or nanoclays have become an attractive class of hybrid materials due to their prospective use in a great variety of applications from industry to health. For design, synthesis and characterization for potential biomedical nanocomposites, antitumor-active copolymer; poly(DHP-alt-MA) were used to prepare copolymer/clay nanocomposites. The functional copolymers, having a combination of rigid/flexible linkages and an ability of complex-formation with interlayered surface of organo-silicate, and their nanocomposites have been synthesized by interlamellar complex-radical copolymerization of intercalated monomer complexes of maleic anhydride (MA) and 3,4-Dihydro-2H-pyran (DHP) with three alkyl ammonium salts surface modified bentonite and monomer mixtures. Poly(DHP-alt-MA) pristine copolymer and poly(DHP-alt-MA)/organically modified bentonite nanocomposites were characterized by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), HR-Raman, X-ray diffraction (XRD) and TEM methods.     

A Single-Gallery Model for the In Situ Production of Polyethylene-Clay Nanocomposites

Polyolefin-clay nanocomposites are finding many new applications because of their improved properties, such as high modulus, elevated scratch resistance and low gas permeability. Currently, these composites are produced by melt blending organically modified clay with polyolefins. The most challenging step in this process is the intercalation and exfoliation of the clay to produce a homogenously dispersed phase at the nanoscale. A promising alternative to melt blending is in-situ polymerization, where the polymer is produced between the clay layers in the polymerization reactor. In-situ polymerization of olefins with metallocene catalysts supported on clay can produce nanocomposites using conventional polymerization reactors, provided that the clay can be used as a support for the olefin polymerization catalyst. In this approach, the clay fulfills the functions of catalyst support and dispersed phase in the final nanocomposite. In this work, a mathematical model describing particle growth during in-situ polymerization of ethylene with a metallocene catalyst supported on clay will be discussed. The model expands the approach of the multi-grain model used in heterogeneous olefin polymerization to account for the layered structure of clays.     

High‐Performance Exfoliated Poly(propylene)/Clay Nanocomposites by In Situ Polymerization with a Novel Z–N/Clay Compound Catalyst

Highly exfoliated poly(propylene) (PP)/clay nanocomposites with obvious improvements in both the tensile strength and toughness have been prepared by a novel TiCl₄/MgCl₂/imidazolium‐modified montmorillonite (IOHMMT) compound catalysts. Through this approach, in situ propylene polymerization can actually take place between the silicate layers and lead not only to PP with a high isotacticity and molecular weight, but also to a highly exfoliated structure even at high clay content levels (as high as 19 wt.‐%).

     

聚苯乙烯/有机合成锂皂石纳米复合材料的制备与表征

聚苯乙烯/有机合成锂皂石纳米复合材料的制备与表征     

阳离子聚氨酯/CeO2纳米复合材料的制备

二氧化铈;阳离子聚氨酯/CeO2纳米复合材料的制备     

The Electrochemical Investigation of MEH-PPV in Ionic Liquid

Ionic liquids are a new kind of room-temperature molten organic salts. It can be used as solvents in the organic/polymeric syntheses, and some of them are called "green" solvents because of its recyclability1. Ionic liquids possess the superior properties, such as thermal stability up to 200(C, involatility and re-designability(for both cation and anion). The ionic liquid employed in this work is [bmim] [PF6]- ( butylmethylimidazolium hexafluorophosphate ) which is immiscible with water and h…     

Exfoliated Polylactide/Clay Nanocomposites by In‐Situ Coordination–Insertion Polymerization

Poly(L ‐lactide)/layered aluminosilicate nanocomposites were synthesized in bulk by ring‐opening polymerization in the presence of two organo‐modified montmorillonites. When the organo‐modifier consisted of an ammonium cation bearing primary hydroxyl groups, polymerization was initiated by the alcohol functions after adequate activation. The growing polymer chains were directly “grafted” onto the clay surface through the hydroxyl‐functionalized ammonium cations yielding exfoliated nanocomposites with enhanced thermal stability.

TEM image of a fully exfoliated Cloisite®30B‐based nanocomposite, showing delamination of the silicate layers.     

等离子体引发原位聚合制备凹凸棒土/聚苯乙烯纳米复合物

用阳离子表面活性剂处理凹凸棒土（Attapulgite),通过超声分散的方法将其均匀分散到苯乙烯单体中，并采用等离子体引发的方法制备出凹凸棒土／聚苯乙烯纳米复合物。通过透射电子显微镜（TEM）和X－射线衍射（XRD）观察了凹凸棒土及其纳米复合物的微观结构。对复合物的GPC测试表明，采用等离子体引发聚合反应可以显著提高树脂的分子量。XRD结果表明聚苯乙烯不是嵌入到凹凸棒土的层间，而是通过离子吸附接枝在凹凸棒土的棒状晶束上。     

悬浮缩聚法制备酚醛树脂/蒙脱土纳米复合材料

采用悬浮缩聚方法在酸性催化剂作用下制备了酚醛树脂/蒙脱土纳米复合材料。以三种不同的蒙脱土：天然土、带有脂肪链季铵盐修饰蒙脱土和带有苯环基团的插层剂修饰的蒙脱土为原料制备了纳米复合材料,并考察了不同插层剂对纳米复合材料形貌的影响,发现带有苯环的插层剂修饰的蒙脱土与酚醛树脂的相容性能更好;研究了固化过程对纳米复合材料形貌的影响,XRD和TEM的结构表明固化过程可以促进带有脂肪链季铵盐修饰的蒙脱土进一步剥离,对其他两类的影响不大;此外还用TGA研究了纳米复合材料的热性能。     

插层聚合聚丙烯-蒙脱土纳米复合材料的微观结构形态

使用偏光显微镜，扫描电镜，透射电镜和广角X射线衍射法研究了插层聚合法制备的聚丙烯－蒙脱土（PP－MMT）纳米复合材料的微观结构和形态发展。结果表明，随着插层聚合反应的进行，较大的初级MMT粒子逐渐剥离成较小的次级粒子。次级粒子由2－20片的单个MMT片层组成，其层间充满了PP分子链。提出了插层聚合过程中PP－MMT复合材料的形态发展模型。另外，MMT的加入对PP的球晶形态也有重要影响，PP完整的球晶随MMT的加入逐渐变小和趋于扭曲甚至破坏。     

PTh / ZnO复合纳米粉的固相合成及其光谱特性

0引言导电聚合物/无机物纳米复合材料具有纳米材料和导电聚合物的共同特性,因此在电催化、二次充电电池材料、超级电容器材料等方面具有良好的应用前景[1]。聚噻吩(PTh)以及取代聚噻吩是导电聚合物领域中较早发现的具有环境稳定性和可加工性的材料之一。近年来,有关聚噻吩/无机物纳米复合材料的制备及其光电性能的研究倍受关注,Gebeyehu等[2]用PTh敏化纳米晶TiO2光伏电池,发现其光伏效率明显优于固态光伏电池;Jayant等[3]研究了PTh中的羧基基团的影响以及在纳米晶TiO2     

Quantitative Characterization of Clay Dispersion in Polymer-Clay Nanocomposites

Summary: A novel methodology has been developed to describe the microstructure of polymer-clay nanocomposites quantitatively. It builds on the image analyses of transmission electron microscopy and optical microscopy micrographs, and two parameters, degree of dispersion and mean interparticle distance per unit volume of clay, are proposed to characterize the level of clay dispersion. It provides insights into the ‘real’ clay dispersion using a combination of both microscopical and macroscopical aspects.     

Effects of annealing treatment on the properties of MEH-PPV/titania hybrids prepared via in situ sol-gel reaction

A uniform poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV)/titania hybrid film was successfully prepared by an in situ sol-gel reaction of titanium isopropoxide (TIP) in the presence of MEH-PPV/2-chlorophenol solution. The annealing treatment increased the conversion of TIP to titania as determined from evidence of the formation of Ti-O-Ti bonds in the Fourier transform infrared (FTIR) spectrum. Scanning electronic microscope (SEM) photographs showed that the morphology and distribution of titania in the hybrid film were strongly related to the amount of water in the in situ sol-gel reaction. The thermal stability of MEH-PPV/titania hybrids was enhanced by the annealing treatment. Small angle X-ray scattering (SAXS) and X-ray diffraction (XRD) analyses indicated that annealing treatment promoted the ordered aggregation of the MEH-PPV chains and crystallization of titania to a certain extent. The blue shift in Ultraviolet-visible (UV-vis) absorption of pure MEH-PPV after annealing was ascribed to the small extent of decomposition and coil conformation which occurred at high temperature. A more-obvious blue shift for the hybrids was observed, which resulted from irregular aggregation and coil conformation of the MEH-PPV chains induced by heterogeneous point, TIP (titania). The red shift in the photoluminescent (PL) emission for pure MEH-PPV resulted from a certain extent of ordered aggregation after annealing. However, only a slight red shift in the PL emission peak for the hybrids was found due to the hindrance of ordered aggregation of MEH-PPV chains in the presence of TIP (titania).