表面改性对掺杂TiO_2纳米薄膜亲水性的影响

文章采用溶胶-凝胶法制备La3+掺杂纳米TiO2薄膜,实验探讨了硝酸溶液表面改性对掺杂纳米TiO2薄膜亲水性的影响。采用X射线衍射分析不同掺杂浓度纳米TiO2的物相,分别利用扫描电镜与接触角测量仪观察TiO2薄膜表面形貌及其亲水性能。实验表明:经0.1mol/L的硝酸溶液中改性后的La3+掺杂纳米TiO2薄膜具有超亲水性。     

纳米TiO_2在泡沫镍上的负载技术研究

采用溶胶-凝胶法制备了锐钛矿型晶体结构的纳米TiO2。以硅溶胶为无机粘结剂,分别采用在含纳米TiO2的乙醇悬浮液中浸涂和直接用悬浮液喷涂的方法,在泡沫镍载体上负载了TiO2催化剂,应用扫描电子显微镜(SEM)对硅溶胶涂层和纳米TiO2催化剂的负载状态进行了分析。研究结果表明,硅溶胶与泡沫镍结合牢固,涂层分布均匀。就TiO2的分散性和负载均匀性而言,喷涂负载优于浸涂负载。采用不同的喷涂次数,可以明显改变纳米TiO2在粘结剂表面的负载量和负载状态。当喷涂次数为1次时,负载的TiO2颗粒呈单分散状态;喷涂次数增加时,会出现纳米颗粒的堆积,但不同于浸涂时的团聚;喷涂5次时,纳米颗粒在泡沫镍表面形成密集层状分布。     

反式聚异戊二烯/多壁碳纳米管复合材料的微观结构及物理机械性能

以氯化镁（MgCl_2）、经四氯化钛（TiCl_4）预处理的普通型多壁碳纳米管（MWCNTs）或羟基化多壁碳纳米管（MWCNTs-OH）为载体,采用高能球磨法制备了负载钛系催化剂,然后采用原位聚合法制备了反式聚异戊二烯（TPI）/MWCNTs纳米复合材料,表征了MWCNTs在催化剂中的分散性、纳米复合材料的微观结构,考察了2种MWCNTs含量对纳米复合材料物理机械性能的影响。结果表明,在负载钛系催化剂中,MWCNTs-OH或普通型MWCNTs无聚集且分散均匀;在2种TPI/MWCNTs复合材料中,TPI分子链紧密包覆MWCNTs表面,二者形成类似于核-壳管状结构,反式-1,4-结构质量分数均为99.1%,3,4-结构质量分数均为0.9%,MWCNTs的类型对复合材料的结构无显著影响;TPI/MWCNTs-OH复合材料的物理机械性能优于TPI/普通型MWCNTs复合材料及纯TPI材料,且当MWCNTs-OH的质量分数达到0.10%时,复合材料的拉伸强度及扯断伸长率较纯TPI分别提高了36%和49%。     

MWCNT/TiO_2复合材料的制备、表征及光催化降解植物多酚的研究

以钛酸丁酯为前驱体,以表面改性后的多壁碳纳米管(MWCNT)为载体,采用溶胶-凝胶法制备出TiO2粒子负载在碳纳米管表面的复合光催化剂,通过XRD、TEM、IR、UV-vis等手段对复合材料进行了表征。结果表明,TiO2均匀包覆在碳纳米管的表面,经500℃煅烧2 h后,纳米TiO2以锐钛型为主,粒径约15 nm,复合材料在紫外区及可见光区对光都有优良的吸收性能。并研究了MWCNT/TiO2光催化剂在紫外灯照射下对单宁酸(模拟栲胶)光催化降解情况,以CODcr的变化评价溶液中栲胶的降解情况。结果表明,在光照6 h后,溶液CODcr值从初始的3 024降到2 000,而用纯TiO2要达到相同的效果需要20 h以上。说明复合材料对单宁酸有很好的光催化降解效果,对研究制革植鞣废水的处理提供了参考。     

环氧树脂/改性碳纳米管复合材料的导热性能

采用硝酸氧化开口、银（Ag）填充和1,6己二胺接枝3种方法对多壁碳纳米管（MWCNTs）进行了改性,并用熔融共混法分别制备了各环氧树脂/改性MWCNTs纳米复合材料,通过扫描电子显微镜、透射电子显微镜、红外光谱等对复合材料的性能进行了测试。结果表明,各改性MWCNTs在环氧树脂中分散均匀,与树脂结合紧密无空隙;复合材料的热导率显著提高,其中改性MWCNTs含量为2.2 %（质量分数,下同）的开口多壁碳纳米管（Opened MWCNTs）和Ag填充多壁碳纳米管（Ag-filled MWCNTs）复合材料的热导率均达到0.20 W/（m·K）,比纯环氧树脂提高了33.3 %。     

“水悬浮法”重氮化改性碳纳米管及其环氧复合材料

以水为溶剂,采用"水悬浮法"对多壁碳纳米管(MWCNTs)进行重氮化改性,然后将改性碳纳米管分散在环氧树脂中制备MWCNTs/环氧纳米复合材料。通过傅里叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)、热重分析法(TG)、沉降性实验和扫描电子显微镜(SEM)等多种手段对改性多壁碳纳米管的结构和纳米复合材料的断面形貌进行表征。研究结果表明:通过重氮化反应在MWCNTs表面成功接枝上了苯甲酸基团,接枝率约为12%。改性MWCNTs在环氧树脂中具有良好的分散性,对环氧树脂具有较好的増韧效果。当改性MWCNTs的添加质量分数为0.3%时,纳米复合材料的拉伸强度和冲击强度最佳,与未改性MWCNTs/环氧树脂复合材料相比分别提高14.8%和462.33%。     

海藻酸钠修饰碳纳米管的制备及性能北大核心

通过海藻酸钠(SAL)修饰多壁碳纳米管(MWNTs),改善MWNTs的水溶性和分散性。用1-乙基-3(3-二甲基氨基丙基)碳化二亚胺(EDC)为偶联剂,在水介质、弱酸性条件下,用超声波辅助法接枝水溶性高分子——海藻酸钠,得到修饰的碳纳米管复合物。红外光谱分析表明,多壁碳纳米管上的—COOH与海藻酸钠上的—NH2反应生成了—NHCO—,证明了MWCNTsSAL的生成,透射电镜测试显示海藻酸钠修饰的MWCNTs在乙醇中能够有效地克服团聚倾向;水溶性实验表明,改性后MWCNTs在水中具有分散性,并能够保持长时间的溶解能力。MWCNTs经SAL修饰后,改善了水溶性和分散性。     

硝酸氧化对多壁碳纳米管的表面修饰及其分散性

采用硝酸氧化法对多壁碳纳米管(MWNTs)进行了表面修饰,通过红外光谱和热重分析等测试手段对其结构特性进行了分析,并对多壁碳纳米管在水中的分散性进行了研究。结果表明,采用硝酸氧化法在多壁碳纳米管的侧壁成功引入了羧基官能团,羧基含量受硝酸浓度、氧化温度和时间的影响。表面修饰后的多壁碳纳米管在水中的分散性和稳定性明显提高。     

多壁碳纳米管对电极染料敏化太阳能电池的制备及电化学性能

以钛酸丁酯为钛源,F：SnO2（FTO）为导电玻璃载体,通过溶胶–凝胶法制备TiO2光阳极;并用3种不同多壁碳纳米管（multi-walled carbon nanotubes,MWCNTs）制备对电极。利用X射线衍射仪和热重–差热分析对TiO2光阳极制备过程中晶体结构和热化学变化进行分析;采用扫描电子显微镜、红外光谱...     

纳米TiO2粉体分散性的研究

以钛酸丁酯为原料,无水乙醇为溶剂,浓硝酸为酸度控制剂,冰醋酸为抑制剂,用溶胶-凝胶法制备粒径为10nm左右的纳米TiO2粉体。并通过表面活性剂和共沸蒸馏来改善纳米TiO2粉体的团聚,结果表明部分阴离子表面活性剂和非离子表面活性剂对纳米TiO2粉体的团聚改善较明显,而阳离子表面活性剂对粉体的团聚改善不明显;共沸蒸馏对粉体的团聚改善也较显著。     

多壁碳纳米管的有机修饰与表征

为了增加多壁碳纳米管(MWCNTs)表面活性,通过浓H2SO4和浓HNO3处理过的MWCNTs与SOCl2回流进而与合成的N-乙基-3,6-二氨基咔唑反应,得到了有机修饰的MWCNTs.用傅立叶变换红外(FTIR)光谱对有机修饰的MWCNTs结构进行研究.研究结果结构表明:有机修饰的MWCNTs红外光谱在1617和16...     

碳纳米管/苯丙乳液导电内墙涂料的制备

先利用混酸体系和3-氨丙基三乙氧基硅烷偶联剂(KH550)对多壁碳纳米管(MWCNTs)进行表面修饰,然后将修饰后的MWCNTs加入苯丙乳液中,成功制备了具有良好抗静电性能和力学性能的碳纳米管/苯丙乳液改性内墙涂料。利用透射电镜,对修饰前后的MWCNTs进行了热重分析。结果表明:KH550成功地接枝到MWCNTs表面,修饰后的MWCNTs能实现很好的分散。研究了MWCNTs用量对所制备涂料的导电性能、力学性能的影响。研究表明当MWCNTs添加量达到2.50%时,涂料的表面电阻最小,为1.42×107Ω,力学性能最佳。     

多壁碳纳米管的改性及其复合材料的制备

用H2SO4/HNO3（体积比3∶1）对碳纳米管进行改性,结果研究表明：与原始碳纳米管相比,改性后的多壁碳纳米管的自身的分散性非常好,表面带有了更多的-OH和-COOH等官能团,碳纳米管在空气中的热稳定性明显下降,而且在碳酸氢铵与氨水和少量SDBS的混合溶液中分散稳定性更好。然后采用原位聚合的方法制备了多壁碳纳米管/碳酸铝铵复合材料,复合粉体的TEM和XRD表明改性后的多壁碳纳米管可以在碳酸铝铵粉体中进行良好的分散。     

Viscoelasticity and thermal stability of poly(arylene ether nitrile) nanocomposites with various functionalized carbon nanotubes

Poly(arylene ether nitrile) (PEN) nanocomposites containing various functionalized multi‐walled carbon nanotubes (MWCNTs) were prepared through a solution‐casting method. The as‐prepared PEN nanocomposites were investigated using parallel‐plate rheometry and thermogravimetric analysis, aimed at examining the effect of surface functionalization on the dispersion of MWCNTs from the viscoelastic and thermal properties. The linear viscoelasticy results indicated that 4‐aminophenoxyphthalonitrile‐grafted MWCNTs presented better dispersion in the PEN matrix than purified and carboxylic MWCNTs because the corresponding composite showed the lowest rheological percolation threshold, which was further confirmed from scanning electron microscopy, dissolution experiments and solution rheological experiments. The thermogravimetric analysis results revealed that the presence of 4‐aminophenoxyphthalonitrile‐grafted and carboxylic MWCNTs retarded the depolymerization compared with purified MWCNTs, showing a marked increase in the temperature corresponding to a loss of 5 wt% (increased by 14–22 °C) and maximum rate of decomposition (increased by 4–8 °C). Both the state of dispersion and the surface functionalization of MWCNTs are very important to the thermal stability of the PEN matrix. Copyright © 2011 Society of Chemical Industry     

Highly dispersed multi-walled carbon nanotubes in ethanol using potassium doping

We demonstrated the production of an effective dispersion of multi-walled carbon nanotubes (MWCNTs) in ethanol using potassium doping (π-stacking interaction). The homogeneous dispersion of individual MWCNTs was achieved without any contamination or severe disruption at the end caps or periphery of the tubes. Potassium as a doping material, phenanthrene as a nonpolar molecule, and 1,2-dimethoxyethane as a dipole solvent were used for our experiment. From UV-visible spectroscopy and visual observation, it was found that the dispersibility of the MWCNTs in ethanol was about 14 mg/dm³. High resolution transmission electron microscopy and Raman spectroscopy showed that disruption of the end caps of the tubes and severance along the tube axis were rarely found. The scanning electron microscopy and corresponding EDX results indicated that the key to the dispersion mechanism was the potassium doping, which is driven by π-stacking complex formation. We suggest that the dispersion of the MWCNTs was influenced by the potassium doping, which caused the enlargement and separation of the entangled-MWCNT networks, and was not affected by defects or modification of the surface morphology.     

The effect of the degree of deacetylation of chitosan on its dispersion of carbon nanotubes

The effect of the degree of deacetylation (DD) of chitosan biopolymer on the noncovalent surface modification of multiwall carbon nanotubes (MWCNTs) is presented. MWCNTs were modified by chitosan having different degree of deacetylation (61%, 71%, 78%, 84%, 90% and 93%) and UV-Visible spectroscopy was used to evaluate their dispersion efficiency as a function of chitosan concentration and degree of deacetylation. Results showed that the dispersion of MWCNTs could be dramatically improved when using chitosan with the lowest degree of deacetylation (61%DD) possibly due to a higher surface coverage of the MWCNTs. Zeta potential measurements were used to confirm that the chitosan surface coverage on the MWCNTs was twice as high when modifying the nanotubes surface with the 61%DD than when using the 93%DD chitosan. These results suggest that the dispersion of MWCNTs with chitosan can be improved when using chitosan having a degree of deacetylation of 61%. These results are of interest in particular for the improved dispersion of MWCNTs in aqueous solutions such as in drug delivery applications.     

单分散纳米二氧化硅微球表面化学修饰与表征

通过溶胶-凝胶法制备纳米二氧化硅微球,以乙醇作为分散介质,用硅烷偶联剂采用一步法对纳米二氧化硅进行了表面化学修饰。通过X-射线光电子能谱（XPS）、透射电子显微镜（TEM）和傅立叶红外光谱仪（FT-IR）等手段对其改性前后效果进行了分析。研究发现修饰后的纳米二氧化硅微球的疏水性增强;硅烷偶联剂与纳米二氧化硅表面羟基发生了化学反应。     

Surface modification of multiwalled carbon nanotubes via gliding arc plasma for the reinforcement of polypropylene

To increase the applicability of multiwalled carbon nanotubes (MWCNTs), functional groups were generated on the generally inert surface of MWCNTs using gliding arc (GA) plasma. MWCNTs were modified using plasma polymerization with styrene (St) as monomer. The surface compositional and structural changes that occur on MWCNTs were investigated using FT‐IR, Raman spectroscopy, BET surface area, and elemental analysis. Dispersion of the treated MWCNTs in different solvents was evaluated. Transmission electron microscopy images showed that the plasma‐treated MWCNTs had a better dispersion than the untreated ones in nonpolar solvents. Subsequently, MWCNTs‐reinforced polypropylene (PP) composites were prepared by internal batch mixing with the addition of 1.0 wt % MWCNTs. The morphology of MWCNTs/PP nanocomposites was studied through scanning electron microscopy. Observations of SEM images showed that the plasma‐treated MWCNTs had a better dispersion than the untreated MWCNTs either on the composite fracture surfaces or inside the PP matrix. Moreover, the mechanical tests showed that the tensile strength and elongation at break were improved with the addition of polystyrene‐grafted MWCNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

多壁碳纳米管分散性研究

通过对多壁碳纳米管的改性研究,寻找提高碳纳米管分散性的途径。采用NaOH对碳纳米管进行预处理,通过SEM、DSC分析表明,该处理过程对去除多壁碳纳米管中杂质和提高其分散性有积极效果。通过H2SO4和HNO3的混酸处理法与HNO3处理法的对比,知前者对碳纳米管的损失要大于后者,且通过对FTIR的对比分析,后者对碳纳米管的改性效果好于前者。TG、TEM分析表明,聚乙烯醇均匀包覆在碳纳米管表面,碳纳米管分散性较酸处理的有所改进。