聚合物/层状硅酸盐插层纳米复合材料的研究

简述了聚合物 /层状硅酸盐插层纳米复合材料方面的研究进展。阐述了层状硅酸盐的结构与性质以及纳米复合材料形成过程的热力学原理。重点介绍了尼龙、聚丙烯等聚合物的层状硅酸盐插层纳米复合材料的现状和技术发展趋势     

剥离型硅橡胶/黏土纳米复合材料研究

利用层状硅酸盐制备有机 无机纳米复合材料是当前人们研究的热点[1,2 ] ,这类材料具有较常规聚合物 无机填料复合材料无法比拟的优点 ,可以明显改善高分子材料的物理机械性能、热稳定性、气体阻隔性、阻燃性、导电性、光学性等 .一般来说 ,聚合物 层状硅酸盐 (Ｐｏｌｙｍｅｒｌａｙｅｒｅｄｓｉｌｉｃａｔｅ ,ＰＬＳ)纳米复合材料可分为插层型和剥离型两种类型 .插层型纳米复合材料即聚合物插入到硅酸盐层中 ,硅酸盐在近程仍保持原有的有序晶体结构 ,在远程则是无序的 .对弹性体而言 ,硅酸盐含量在插层型杂化材料中的含量比较高 ,力学性能…     

壳聚糖基层状硅酸盐纳米复合材料

壳聚糖基层状硅酸盐纳米复合材料是采用简单的溶液插层法,将壳聚糖及其衍生物插层进入层状硅酸盐的纳米层间而获得的有机无机纳米杂化材料。该材料偶合了壳聚糖及其衍生物和层状硅酸盐的协同优势,为壳聚糖的研发应用开辟了新方向和新途径。本文在对壳聚糖和层状硅酸盐的特性及应用进行简单介绍的基础上,重点综述了壳聚糖基层状硅酸盐纳米复合材料的制备方法、插层机理及应用现状,并提出了目前存在的主要问题。     

新型纳米层状硅酸盐Magadiite主体材料的制备、表征、结构和生成机理研究

利用简单的插层反应方法成功地制备了四丁基氢氧化铵(TBAOH)插层的层状硅酸盐Magadiite纳米复合材料,在室温下该材料溶胶放置30d可以保持稳定,粉体长期保存结构稳定,而且反应时间短,只需30min.利用XRD,FTIR,SEM和HRTEM等方法对样品进行了结构表征.结果表明,TBA⁺离子在层间以双分子层排列,并与层状硅酸盐结合在一起,TBAOH插层后的纳米粒子在玻璃片上进行了重组,粒径分布在10～100nm之间;HRTEM电镜照片进一步证实了剥离的层状硅酸盐纳米粒子在玻璃片上的自组装过程.根据实验结果阐述了TBAOH插层反应形成纳米溶胶的机理.     

茂钛催化剂苯乙烯原位间规聚合制备sPS/蒙脱土纳米复合材料

聚合物基纳米复合材料具有常规有机 /无机复合材料所没有的结构和形态 ,其性能较普通的聚合物复合材料更优异 ,因而引起人们的广泛关注 [1～ 4 ] .近年来的研究表明 ,运用插层聚合和熔融插层等方法可使某些具有层状结构的硅酸盐与聚合物产生特殊的界面作用 ,并以纳米尺寸均匀分     

有机季鏻盐插层改性黏土诱发聚丙烯γ晶

选用有机季鏻盐作为插层剂对黏土进行有机化插层改性,制备出有机黏土,通过熔融插层法制备聚丙烯/有机黏土纳米复合材料.XRD表明有机季鏻盐改性的黏土与聚丙烯形成结构为剥离型与插层型并存的纳米复合材料.利用DSC研究了纳米复合材料的熔融过程,结果显示有机黏土对聚丙烯的结晶度影响不明显.XRD和DSC的研究均表明,有机黏土可以诱发聚丙烯产生不常见的γ晶型.当黏土含量为5 wt%时,γ晶型占整个结晶部分的12%左右.     

有机季鏻盐插层改性黏土诱发聚丙烯γ晶

选用有机季鏻盐作为插层剂对黏土进行有机化插层改性,制备出有机黏土,通过熔融插层法制备聚丙烯/有机黏土纳米复合材料.XRD表明有机季鏻盐改性的黏土与聚丙烯形成结构为剥离型与插层型并存的纳米复合材料.利用DSC研究了纳米复合材料的熔融过程,结果显示有机黏土对聚丙烯的结晶度影响不明显.XRD和DSC的研究均表明,有机黏土可以诱发聚丙烯产生不常见的γ晶型.当黏土含量为5 wt%时,γ晶型占整个结晶部分的12%左右.     

有机染料-层状硅酸盐光活性纳米复合材料*

有机-无机纳米复合材料,尤其是有机客体插层入无机层状固体自组装形成的纳米复合材料,因其独特的微观结构与性能,在超分子构筑纳米材料领域中具有特殊地位。本文主要介绍了光致变色与光致发光光功能性有机染料插层层状硅酸盐纳米复合材料的研究进展,着重讨论了螺吡喃、偶氮、二芳基乙烯、芘、香豆素等染料在二维纳米片层间独特的光学行为、有序排列形态、构筑的多层功能性薄膜及其在光功能性材料开发方面的应用前景。     

聚酰胺6/蒙脱石纳米复合材料的紫外光老化

聚合物 /层状硅酸盐纳米复合材料的研究十分活跃 [1～ 4 ] .聚酰胺 6/蒙脱石 ( PA6/MMT)纳米复合材料与纯聚酰胺 6( PA6)相比 ,模量和强度明显提高 ,耐热性能提高尤为显著 .光氧化行为材料科学领域的重要研究课题 .Admas等 [5]报道在紫外光照射下 ,聚丙烯 /粘土纳米复合材料的氧化速度要比纯聚丙烯的快 .对于 PA6/MMT纳米复合材料的光老化研究尚未见报道 .本文以傅里叶变换红外光谱定量研究手段 ,对比分析了 PA6/MMT纳米复合材料与 PA6的紫外光氧化性能 .1　实验部分　　采用熔体插层技术 ,将 PA6( Honeywell B1 0 0 MP)和有机蒙…     

聚合物/层状硅酸盐纳米复合材料的环境稳定性

过去的十多年里，聚合物／层状硅酸盐纳米复合材料在制备、结构与性能方面的研究取得了长足的进步。一些聚合物基的纳米复合材料已实现工业生产，在汽车、家电和包装等领域得到应用。环境稳定性是聚合物材料应用的一个重要方面。本文从材料的耐候性、耐热性和阻燃性能的角度出发，评述了近年来聚合物／层状硅酸盐纳米复合材料在紫外光降解、热降解和燃烧性能方面的研究进展，以期对纳米复合材料的基础研究及应用开发有所裨益。     

熔体插层聚合物/粘土纳米复合材料

对国内外熔体插层法制备聚合物／粘土纳米复合材料(PCN)的研究进展进行了综述。介绍了影响PCN结构形态的各种因素；对熔体插层法制备PCN的热力学、动力学研究进行了总结；详细讨论了熔体插层的机理研究及理论模型。并对熔体插层法制备PCN提出了展望。     

Nanostructure of montmorillonite barrier layers: A new insight into the mechanism of flammability reduction in polymer nanocomposites

This study describes the mechanism of flammability reduction in flame-retarded polymer matrix organo-montmorillonite reinforced nanocomposites. Morphologies of untested polymer nanocomposites and char residues formed by combustion in the mass loss calorimeter are characterized by XRD and TEM techniques. It is postulated that a combination of well-dispersed montmorillonite platelets and flame retardants in the polymer matrix provides nano-structured char formation. Initial montmorillonite dispersion in flame-retarded nanocomposites is found to be a major controlling factor on formed char nanostructures. An initially intercalated structure is invariantly converted to complete montmorillonite collapse whereas an initially exfoliated structure transforms to nano-structured chars demonstrating retained exfoliation or a new state of intercalation via incomplete collapse of montmorillonite layers. It is proposed that nano-structured char formation is the effective mechanism of flammability reduction, i.e. reduction in rate of heat release during combustion, in flame-retarded polymer nanocomposites.     

聚合物纳米材料研究进展——Ⅱ.聚合物/无机纳米复合材料

复合物纳米材料包括纳米聚合物和聚合物／无机纳米复合材料。本文综述了聚合物／无机纳米复合材料的研究进展，重点介绍了溶胶－凝胶法，原位生成法，模板法，插层复合，沉积法，机械粉碎，分子平壤 ，溶液或融混合法的研究进展。     

Preparation and Characterization of Poly(butyleneterephthalate)/Organoclay Nanocomposites

PBT/organic montmorillonite (MMT) nanocomposites were prepared via melt intercalation and their nanostructure was characterized by means of X‐ray diffraction and transmission electron microscopy. Nanocomposite formation requires sufficiently hydrophobic organically modified layered silicates, as well as the presence of polar interactions between silicate and polymer. Three different alkylammonium surfactants were used to modify MMT. In addition, epoxy resin was added as a third component, and the effects on the intercalation and exfoliation behavior of the PBT nanocomposites were investigated.     

Electrical characterization of poly(ethylene oxide)–clay nanocomposites prepared by microwave irradiation

Poly(ethylene oxide) (PEO)–clay (montmorillonite, hectorite, and laponite) nanocomposites were prepared by a melting intercalation procedure induced by microwave irradiation. The influence of parameters such as the time of irradiation, power, amount and relative ratio of the reagents, and relative humidity was investigated. X-ray diffraction, differential scanning calorimetry, elemental microanalysis, Fourier transform infrared, and scanning electron microscopy techniques were applied to characterize the resulting nanocomposites. Techniques involving impedance spectroscopy, thermoelectric power, and electrical polarization in the solid state were used to characterize the electrical properties of the nanocomposites. The electrical behavior of these PEO–silicate nanocomposites, including those containing an excess of alkaline metal salts in comparison with that of similar systems prepared by alternative procedures such as direct intercalation from polymer solutions or melting intercalation, was also examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3249–3263, 2003     

PMMA/MMT nanocomposites prepared by one-step in situ intercalative solution polymerization

Poly(methylmetacrylate)/montmorillonite (PMMA)/(MMT) nanocomposites were prepared by one-step in situ intercalative solution polymerization involving simultaneous modification of MMT with quaternary ammonium salts (QAS), polymerization and polymer intercalation. Polymerization proceeded at 70 °C in a mixture of ethanol and water, whereas the nanocomposite was precipitated with only water. Four QAS’s with different alkyl chain lengths, as well as a QAS with an additional acrylic group, were used to study the influence of the type of quaternary ammonium salt on intercalation. The largest extent of intercalation was achieved in nanocomposites with the QAS having one long alkyl (C16) chain. The obtained PMMA/MMT intercalated nanocomposites exhibited a higher glass transition temperature, better thermal stability, and improved solvent resistance than the pure PMMA.     

Preparation of poly(propylene)/clay layered nanocomposites by melt intercalation from pristine montmorillonite (MMT)

Poly(propylene)/clay nanocomposites were prepared by melt intercalation, using pristine montmorillonite (MMT), hexadecyl trimethyl ammonium bromide (C16), poly(propylene) (PP) and maleic acid (MA) modified PP (MAPP), The nanocomposites structure is demonstrated using X‐ray diffraction (XRD) and high resolution electronic microscopy (HREM). Our purpose is to provide a general concept for manufacturing polymer nanocomposites by melt intercalation starting from the pristine MMT. We found different kneaders (twin‐screw extruder or twin‐roll mill) have influence on the morphology of the PP/clay nanocomposites. Thermogravimetric analysis (TGA) shows that the thermal stability of PP/clay nanocomposites has been improved compared with that of pure PP. Copyright © 2003 John Wiley & Sons, Ltd.     

Montmorillonite-poly(ethylene oxide) nanocomposites: interlayer alkali metal behavior

Clay-PEO nanocomposites can have large electrical conductivities that make them potential electrolyte materials for rechargeable lithium batteries, but the origin of these large conductivities, especially for Li-containing materials, is poorly understood. This paper presents X-ray diffraction (XRD), TGA-DTA, and (7)Li and (23)Na NMR data for PEO nanocomposites made with natural (SWy-1) and synthetic (MNTS) montmorillonite clays that provide new insight into interlayer structure. An increase in basal d(001)-spacings demonstrates successful intercalation of PEO in all samples, and X-ray line narrowing shows that this intercalation improves the layer stacking order. The basal spacings of 17.9-19.4 A are consistent with a helical or bilayer structure of PEO in the interlayer. TGA-DTA provides quantitative results for the hydration state of the nanocomposites, demonstrates PEO intercalation, and shows that the composites prepared from the synthetic montmorillonite are less stable than those made with SWy-1. (7)Li NMR shows that the nearest neighbor hydration state of Li(+) is unaffected by PEO intercalation and suggests weak interaction of Li(+) with PEO. (23)Na NMR shows that PEO intercalation results in the conversion of the multiple Na(+) hydration states observed for the pristine clay into inner sphere sites most likely formed through coordination with the basal oxygens of the clay. These differences between lithium and sodium suggested that tighter binding of the Na to the clay may be the origin of the conductivity of Li-montmorillonite-PEO nanocomposites being as much as 2 orders of magnitude larger than those of Na-montmorillonite-PEO nanocomposites. The results confirm the idea that polymer oxygen atoms do not participate in sequestering the exchangeable cations and agree with the jump process for cation migration advanced by Kuppa and Manias (Kuppa, V.; Manias, E. Chem. Mater. 2002, 14, 2171).     

Influence of organoclay dispersed state of poly(ethylene glycol‐co‐1,3/1,4‐cyclohexanedimethanol terephthalate)/organoclay nanocomposites on their characteristics

This work prepared poly(ethylene glycol‐co‐1,3/1,4‐cyclohexanedimethanol terephthalate) (PETG)/organoclay nanocomposites via a melt intercalation process and investigated the influences of organoclay aspect ratio and organoclay content on the dispersed state, mechanical, thermal, gas barrier, and heat recovery properties of PETG/organoclay nanocomposites. X‐ray diffraction (XRD) and transmission electron microscopic analyses showed that the organoclay dispersed in the polymer matrix with intercalation in the nanometer scale range. Differential scanning calorimetry (DSC) analysis demonstrated that all of the obtained nanocomposites were amorphous, indicating that the addition of organoclay did not affect the amorphous nature of PETG. The gas barrier properties of the nanocomposites improved with organoclay content and the properties were also affected by the organoclay aspect ratio. Water vapor and oxygen transmission rates (OTRs) of PETG/organoclay nanocomposites containing 3 phr Cloisite 15A, and 3 phr modified polymer grade Na‐montmorillonites (MPGN) were the lowest among the samples tested, and were 41.7 and 44.3%, respectively, of those of neat PETG. Similar organoclay content‐ and aspect ratio‐related effects were observed in the mechanical and heat recovery properties of the tested nanocomposites. Copyright © 2010 John Wiley & Sons, Ltd.