氧化石墨插层纳米复合材料的制备研究进展

氧化石墨（GO）插层纳米复合材料是一种新型的纳米复合材料。介绍了氧化石墨的结构、制备方法和性质；重点论述了聚合物/氧化石墨插层纳米复合材料和无机物/氧化石墨插层纳米复合材料的制备研究进展，介绍了半导体氧化物/氧化石墨插层纳米复合材料。     

聚丙烯酰胺/氧化石墨纳米复合材料的研究

氧化石墨具有良好的层状结构，其层间具有丰富的官能团，能与有机聚合物形成插层纳米复合材料进而改善材料的性能．采用层离吸收-原位聚合法制备了聚丙烯酰胺／氧化石墨纳米复合材料，并采用XRD、HREM及DSC等对其结构和性能进行了表征。结果表明，聚丙烯酰胺与氧化石墨两者之间存在着较强的相互作用，材料的玻璃化转变温度得到提高，层离吸收-原位聚合法是获得聚丙烯酰胺／氧化石墨层纳米复合材料的有效途径，聚丙烯酰胺在氧化石墨中存在着多种排列方式，不同层间距(1．6nm和2．8nm)的聚丙烯酰胺／氧化石墨纳米复合结构同时存在。     

聚吡咯/氧化石墨复合材料的制备及其电容性能

以氧化石墨为载体,采用木质素磺酸钠作为掺杂剂,氯化铁作为氧化剂,引发吡咯单体在氧化石墨层发生化学原位聚合反应,制备了聚吡咯(PPy)/氧化石墨复合材料。通过XRD、FTIR和SEM分析分别对复合材料的物相组成、结构和微观形貌进行了表征,通过TGA分析研究了复合材料的热稳定性,采用恒电流充放电、循环伏安和电化学阻抗谱等方法测试分析其电化学性能。研究表明:采用化学原位聚合的方法合成的PPy/氧化石墨复合材料具有"层-球"状的"三明治"型微观结构,以便形成良好的导电网络,其结晶度高、排列规整、缺陷少,复合材料中吡咯单体通过N-H键与氧化石墨的含氧官能团发生键合。PPy/氧化石墨复合材料新颖的微观结构和良好的化学键合状态使其表现出优异的电容性能。在电流密度分别为0.5、1.0、2.0和5.0 A/g时的比电容分别为500、460、427和396 F/g;经过1000次恒电流(2.0 A/g)充放电循环后, PPy/氧化石墨复合材料的比电容保持率为97.2%。      

环氧树脂/粘土纳米复合材料的制备与性能研究

研究了有机蒙脱土在环氧树脂中的插层和剥离行为,制备了两种环氧树脂/蒙脱土纳米复合材料并测试了其力学性能。实验结果表明,环氧树脂与有机土的相容性好,二者混合时环氧树脂很容易插入到粘土层间。使用经不同有机阳离子处理的两种有机蒙脱土,分别制得插层型和剥离型环氧/粘土纳米复合材料,力学性能结果表明,剥离型纳米复合材料的性能优于同组成的插层型纳米复合材料。     

氰酸酯树脂/氧化石墨烯纳米复合材料的制备及表征

通过溶液插层的方法制备氰酸酯树脂/氧化石墨烯纳米复合材料,采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和热重分析(TGA)研究纳米复合材料的结构和性能,采用电子万能试验机研究纳米复合材料的力学性能。研究表明,异氰酸苯酯改性氧化石墨在二甲基甲酰胺中经超声处理后剥离形成氧化石墨烯薄片;添加氧化石墨烯后纳米复合材料的力学性能和耐热性显著改善。当氧化石墨烯的含量为基体树脂的1%时,纳米复合材料的拉伸强度、弯曲强度和冲击强度分别为82.9 MPa、148.6 MPa和12.9 kJ/m2,1000℃时的残炭率达45.1%。     

PMAA/MMT及PMAA/MMT/SiO_2纳米复合材料的结构与性能研究

采用原位插层聚合法制备了聚甲基丙烯酸/蒙脱土(PMAA/MMT)纳米复合材料和聚甲基丙烯酸/蒙脱土/二氧化硅(PMAA/MMT/SiO2)纳米复合材料,并比较两种纳米复合材料的结构与性能。研究结果表明,PMAA/MMT纳米复合材料属于插层与剥离共存型纳米复合材料。PMAA/MMT/SiO2纳米复合材料中蒙脱土的特征衍射峰已经消失,蒙脱土与二氧化硅均匀分散在聚合物基体中。PMAA/MMT及PMAA/MMT/SiO2纳米复合材料均有一定的鞣制性能,但相对而言PMAA/MMT/SiO2纳米复合材料的鞣制效果较好。     

聚吡咯/多壁碳纳米管复合材料的制备与性能研究

以吡咯为单体、三氯化铁为氧化剂,采用反相微乳液聚合法,分别在十二烷基苯磺酸钠(SDBS)溶液中和含有多壁碳纳米管(MWCNTs)的十二烷基苯磺酸钠(SDBS)溶液中,通过化学氧化法制得了聚吡咯纳米颗粒和聚吡咯/多壁碳纳米管(PPy/MWCNTs)导电复合材料。利用SEM、TEM、FT-IR、XRD和四探针电导率仪对复合材料进行了表征。结果表明,当SDBS浓度为0.0120mol/L时所制备的聚吡咯纳米颗粒的电导率在1.00S/cm左右;在含有MWCNTs的SDBS溶液中,单体在SDBS的胶束内聚合,表面活性剂及其胶束吸附在MWCNTs的表面,表面活性剂的浓度和碳纳米管的用量对PPy/MWCNTs复合材料电导率的提高起到重要作用。当SDBS浓度为0.0120mol/L、MWCNTs和单体的质量比为0.20时,可获得电导率为5.68S/cm的PPy/MWCNTs纳米复合材料。     

超声波对硅树脂/蒙脱土纳米复合材料热性能的影响

采用超声波技术,原位插层聚合法制备了甲基苯基硅树脂/有机蒙脱土(OMMT)纳米复合材料。X射线衍射(XRD),透射电镜(TEM)研究了复合材料内部结构以及超声波时间对蒙脱土分散性和复合材料热性能的影响。简单控制超声波时间15和30min,分别制备了不同OMMT质量分数的插层型和剥离型聚合物/蒙脱土纳米复合材料。加入OMMT,无论是插层型还是剥离型,复合材料的起始分解温度都有所下降,但热失重速率较平缓。插层型纳米复合材料耐热性能明显优于剥离型,温度500℃时,插层型热失重均小于纯硅树脂。当OMMT含量8%时,插层型PLS复合材料500℃的热失重均10%;而剥离型PLS复合材料500℃的热失重较大,超过15%。     

聚吡咯衍生物-过渡金属氧化物纳米复合材料的制备与表征

以水作为溶剂,将水溶性吡咯衍生物单体(碘化N,N,N-三甲基-(2-吡咯-1-乙基))与V2O5溶胶混合,进行原位插层聚合反应,合成PTPAI/V2O5插层纳米复合材料.采用XRD,FT-IR和SEM对其结构和形貌进行了分析.聚(N,N,N-三甲基-(2-吡咯-1-乙基)/V2O5的doo1面间距从10.7739nm增大到13.5436nm,表明聚吡咯衍生物已插入V2O5干凝胶的层间,其FT-IR光谱说明聚吡咯与V2O5层存在着较强的相互关系,SEM图谱揭示了聚(N,N,N-三甲基-(2-吡咯-1-乙基)在V2O5层间附着的形貌特征.     

新型抗凝血纳米复合材料的制备及其性能研究

利用溶液插层法合成了新型的硅橡胶/氧化石墨-十六烷基三甲基溴化铵-肝素抗凝血纳米复合材料.通过FT-IR、XRD、SEM和机械性能测试了解改性氧化石墨微观纳米结构对材料宏观性能的影响;溶血试验和血小板粘附试验测定表明硅橡胶/改性氧化石墨抗凝血纳米复合材料的血液相容性得到极大的改善;这种新型的、兼具优良血液相容性和良好力学性能的复合材料可望在生物医学工程方面得到应用.     

Graphite oxide/poly(methyl methacrylate) nanocomposites prepared by a novel method utilizing macroazoinitiator

Graphite oxide (GO)/poly(methyl methacrylate) (PMMA) nanocomposites were prepared by a novel method utilizing macroazoinitiator (MAI). The MAI, which has a poly(ethylene oxide) (PEO) segment, was intercalated between the lamellae of GO to induce the inter-gallery polymerization of methyl methacrylate (MMA) and exfoliate the GO. The morphological, conductivity, thermal, mechanical and rheological properties of these nanocomposites were examined and compared with those of intercalated nanocomposites prepared by polymerization with the normal radical initiator, 2,2′-azobisisobutyronitrile. The improvement in conductivity by GO was more evident in exfoliated nanocomposites compared to that of intercalated nanocomposites. For example, a conductivity of 1.78 × 10⁻⁷ S/cm was attained in the exfoliated nanocomposite prepared with 2.5 parts GO per 100 parts MMA, which was about 50-fold higher than that of the intercalated nanocomposite. The thermal, mechanical and rheological properties also indicate that thin GO with a high aspect ratio is finely dispersed and effectively reinforced the PMMA matrix in both exfoliated and intercalated nanocomposites.     

Dielectric properties of montmorillonite clay filled poly(vinyl alcohol)/poly(ethylene oxide) blend nanocomposites

Organic–inorganic nanocomposites of poly(vinyl alcohol) (PVA)–poly(ethylene oxide) (PEO) blend filled with montmorillonite (MMT) nanoclay up to 10 wt.% concentration were synthesized by aqueous solution-cast technique. The complex dielectric function, electrical conductivity, electric modulus and impedance spectra of the nanocomposites were measured in the frequency range 20 Hz–1 MHz at ambient temperature. A direct correlation was observed between the real part of dielectric function and the mean relaxation time of the polymer chain segmental dynamics, with the exfoliated and intercalated MMT clay structures, and the extent of miscibility between PVA and PEO due to hydrogen bonded bridging through exfoliated MMT clay nanosheets. The large increase of dielectric relaxation time revealed that the dispersed exfoliated nanoscale MMT clay in the polymers blend matrix produces a large hindrance to the polymer chain dynamics. Results confirm that the real part of dielectric function of the nanocomposites can be tailored by varying amount of MMT clay filler for their use as nanodielectric materials in the microelectronic technology.     

Improvement of electric conductivity of LLDPE based nanocomposite by paraffin coating on exfoliated graphite nanoplatelets

Paraffin coated exfoliated graphite nanoplatelets (xGnP) reinforced with Linear Low-Density PolyEthylene (LLDPE) nanocomposites have been fabricated and characterized for mechanical, electrical and morphological properties. Paraffin was added to decrease the percolation threshold of electric conductivity. LLDPE–paraffin/xGnP nanocomposites were prepared by separate solution and total solution mixing methods. The mixture master batch of each mixing method was injection-molded to produce composites with a mini twin-screw extruder. The separate mixing method was not suitable since there was not enough electrical conductivity due to the low xGnP content in the nanocomposites. However, paraffin does not affect mechanical properties until around 30 wt% of content has been added, even though the content is low molecular weight polyethylene. When the total mixing method was used, the adding content of xGnP and paraffin was easily controlled. Five weight percentage of xGnP loaded nanocomposite showed electrical conductivity when 10 wt% of paraffin was added. From the results of SEM images of fracture surface and DSC, it could be seen that Paraffin was well coated on xGnP, resulting in a separate phase between xGnP and LLDPE. By coating paraffin on xGnP in the LLDPE matrix, the percolation threshold dramatically decreased compared to the xGnP–LLDPE nanocomposite.     

纳米有机蛭石/天然橡胶复合材料的制备及性能

以十六烷基三甲基溴化铵为插层剂, 用球磨法对蛭石进行了快速有机插层, 用过熔融共混法制备出纳米有机蛭石/ 天然橡胶复合材料。用XRD、SEM、TEM 对其微观结构进行了表征与分析, 证明蛭石以纳米片层分散在天然橡胶基体中。力学性能测试表明: 复合材料拉伸强度、扯断伸长率、300 %定伸强度、邵氏A 硬度、撕裂强度得到明显的改善。DMA、DSC 测试表明: 复合材料的模量具有明显的提高, 而玻璃化转变温度无明显变化。可见有机插层蛭石对天然橡胶的综合性能具有较明显的改善作用。      

Studies on the preparation and structure of polyacrylamide/α-zirconium phosphate nanocomposites

In this paper, a novel polyacrylamide(PAM)/α-zirconium phosphate(α-ZrP) nanocomposite was successfully synthesized by exfoliation-adsorption and in-situ intercalative polymerization. The microstructure of PAM/α-ZrP nanocomposites was confirmed by X-ray diffraction measurement, transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM). The results suggested that the α-ZrP lamellae were dispersed well in PAM matrix, which indicated the formation of the exfoliated nanocomposites in the low inorganic loading of α-ZrP (≤5 wt%). With the increase of the inorganic loadings, the intercalated structure of PAM/α-ZrP nanocomposites was dominant with the d-spacings of about 1.50–1.58 nm corresponding to the inorganic loadings in the range of 10–20 wt%. Moreover, besides the electrostatic adsorption, it was also found that there may be some weak effect such as hydrogen bonding or protonation between the host and guest investigated using fourier transform infrared spectroscopy (FT-IR) and thermogravimetric (TG )analysis, which resulted in the enhancement of the thermal properties on the decomposition process of PAM/α-ZrP nanocomposites by the retardant effect of the exfoliated or intercalated α-ZrP nanometer lamellae.     

Preparation and characterization of gold/poly(vinyl alcohol)/MoS2 intercalation nanocomposite

Gold-molybdenum disulfide nanocomposites were prepared by means of exfoliation of a layered host and subsequent in situ oxidation–reduction of the intercalated auric compounds, using the interlayer of MoS₂ as the nanoreactor and poly(vinyl alcohol) (PVA) molecules as the dispersant. The nanocomposites were characterized by means of powder X-ray diffraction, Fourier transformation infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electrical conductivity of the Au/PVA/MoS₂ nanocomposites at various temperatures was investigated. Results indicated that Au and PVA were intercalated in the layered MoS₂, at an interlayer distance of 2.072 and 0.928 nm. The intercalation of Au and PVA led to a significant increase in the electrical conductivity value of MoS₂, while the electrical conductivity value of the intercalation nanocomposites decreased with decreasing temperature.     

Preparation of polymer/LDH nanocomposite by UV-initiated photopolymerization of acrylate through photoinitiator-modified LDH precursor

The exfoliated polymer/layered double hydroxide (LDH) nanocomposite by UV-initiated photopolymerization of acrylate systems through an Irgacure 2959-modified LDH precursor (LDH-2959) as a photoinitiator complex was prepared. The LDH-2959 was obtained by the esterification of 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) with thioglycolic acid, following by the addition reaction with 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), finally intercalation into the sodium dodecyl sulfate-modified LDH. For comparison, the intercalated polymer/LDH nanocomposite was obtained with additive Irgacure 2959 addition. From the X-ray diffraction (XRD) measurements and HR-TEM observations, the LDH lost the ordered stacking-structure and well dispersed in the polymer matrix at 5 wt% LDH-2959 loading. The glass transition temperature of UV-cured exfoliated nanocomposites increased to 64 °C from 55 °C of pure polymer without LDH addition. The tensile strength was improved from 10.1 MPa to 25.2 MPa, as well the Persoz hardness enhanced greatly, while the elongation at break remained an acceptable level.     

Layered double hydroxide as nanofiller in the development of polyurethane nanocomposites

Polyurethane (PU)/Dodecyl sulphate intercalated layered double hydroxide (DS-LDH) nanocomposites were successfully synthesized from PU prepolymer and polyol TG (mixtures of glycerol and trimethylolpropane) for the first time. Formation of partially exfoliated structures of PU/DS-LDH nanocomposites was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Analysis of tensile properties showed significant improvements in tensile strength (TS) and elongation at break (EB) of about 407% and 83% for PU/DS-LDH (3 wt%) nanocomposite. The observed excellent concurrent improvement in TS and EB is attributed to the relatively better reinforcing effect of partially exfoliated DS-LDH layers in PU making the present investigation most noteworthy. In addition, gradual improvement in thermal stability and limiting oxygen index (LOI) with increasing DS-LDH loading makes these nanocomposites versatile and hence suitable for many critical applications.     

Hybridization of kaolinite by consecutive intercalation: Preparation and characterization of hyperbranched poly(amidoamine)–kaolinite nanocomposites

Different nanocomposites based on virgin as well as treated kaolinites, as dispersed phases, and hyperbranched poly(amidoamine) (PAMAM) as a continuous phase were formulated using aqueous dispersion method. The interactive forces between the phases were evidenced using different techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscope (TEM), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results showed that intercalation of PAMAM took place in pre-expanded kaolinite to give exfoliated nanocomposite. However, virgin kaolinite was successfully intercalated with PAMAM without pretreatment to give a nanocomposite of intercalated type with a basal space of about 47 Å. All samples exhibited lower Tg values along with worsened thermal stability compared to the parent polymer.