表面引发原子转移自由基聚合制备聚电解质修饰的碳纳米管

利用聚电解质对多壁碳纳米管(MWNT)的表面进行修饰,能有效改善碳纳米管在溶剂中的分散性.首先将经硝酸氧化的碳纳米管与二甲亚砜和乙二醇反应,得到羟基修饰的碳纳米管.然后利用羟基与α-溴异丁酰溴(或α-氯丙酰氯)的酯化反应,在碳纳米管的表面引入了原子转移自由基聚合(atom transfer radical polymerization,ATRP)引发基团,引发丙烯酸叔丁酯(tBA)或4-乙烯基吡啶(4VP)聚合,通过投料比的改变,得到接入量不同的聚合物修饰的碳纳米管.利用热重分析(TGA)和红外对聚合物修饰的碳纳米管进行表征.将聚合物修饰的碳纳米管进行水解(或季胺化),制备得到在水溶液中良好分散的聚电解质修饰的碳纳米管.     

纳米SiO_2表面引发接枝含短全氟碳侧链嵌段共聚物P(MMA-b-C_6SA)的合成及其性能研究

通过ARGET ATRP(电子转移催化剂再生原子转移自由基聚合)法,以甲基丙烯酸甲酯(MMA)、丙烯酸[N-甲基全氟己烷磺酰胺基]乙酯(C_6SA)为单体,利用干式化学接枝法合成的SiO_2-NH-Br为引发剂,分步接枝得到了表面性能优异的有机/无机复合微-纳结构材料SiO_2-P(MMA-b-C_6SA).该材料经氢氟酸刻蚀后,采用凝胶渗透色谱(GPC)测定了接枝聚合物的分子量及其分布,结果表明在纳米SiO_2表面生长出了分子结构可控的嵌段聚合物.透射电镜观察SiO_2-P(MMA-b-C_6SA)复合物形貌呈现均匀分散的球形颗粒,表明所制备的有机/无机复合物在有机溶剂中具有良好的分散性.热重分析结果表明,该材料化学结构均一,并具有良好的热稳定性.本文采用具有工业应用前景的ARGET ATRP法,将环境友好的含氟单体(C_6SA)接枝在无机粒子表面,赋予其低表面能特性,使其水接触角达到143°,HD的静态接触角达到90°,表现出了优异的疏水疏油性能,并具有自清洁的性能.     

ATRP法合成弹性蛋白接枝共聚物及其性能研究

弹性蛋白经α-溴异丁酰溴化制备了大分子ATRP引发剂溴化弹性蛋白(E-Br), 再以E-Br作为引发剂, 在CuCl/2,2-联吡啶催化体系下, 用原子转移自由基聚合方法合成了弹性蛋白-g-聚甲基丙烯酸-β-羟乙酯接枝聚合物. 用红外光谱(FTIR)、X射线光电子能谱(XPS)、热重分析(TGA)、扫描电镜(SEM)、离子色谱和动态接触角对接枝聚合物进行了表征. 结果表明, PHEMA键接到了弹性蛋白表面; SEM显示接枝改性后弹性蛋白的表面比未改性前光滑, 但改性后样品的热性能均比未改性样品的低, 起始热分解温度由改性前的307 ℃变为265 ℃; 动态接触角实验结果表明, 接枝改性后的样品具有良好的亲水性, 反应72 h后, 其前进角由接枝前的130.45°下降到29.80°.     

含氟聚合物(PPFGs)的制备及其构筑疏水棉布的性能研究

采用五氟苯乙烯(PFS)和甲基丙烯酸缩水甘油酯(GMA)为原料,调控PFS和GMA摩尔比例制备了一系列含氟聚合物(PPFGs),利用PPFGs支链末端环氧基团与基体棉布表面羟基发生化学反应来提高棉布的疏水性能及其耐久性能。通过对PPFGs处理棉布的接触角和形态形貌分析测试表明,含氟聚合物PPFG2化学键合处理的棉布不仅具有良好的疏水性能,还表现出优异的疏水耐久性能,因而利用该含氟聚合物PPFGs构筑疏水涂层具有良好的应用前景。     

表面接枝聚甲基丙烯酸二甲氨乙酯的pH响应型纤维素纸基材料

使用电子转移再生引发剂原子转移自由基聚合(ARGET ATRP)在滤纸表面接枝聚甲基丙烯酸二甲胺乙酯(PDMAEMA),成功制备了具有p H响应性能的新型纤维素纸基材料.分别在苯甲醚和甲醇中进行该接枝聚合反应,发现在甲醇中接枝效率更高.通过游离引发剂生成的均聚物研究了滤纸表面聚合物侧链的分子量及分子量分布.均聚物的GPC曲线表明聚合物分子量随反应时间增加而增加,分子量分布为1.4~1.6.通过FTIR、SEM及接枝率的测量对改性滤纸进行表征,结果表明PDMAEMA在滤纸表面的接枝聚合具有可控性,通过控制反应时间可控制聚合物在滤纸表面的接枝量.在不同p H条件下对改性滤纸进行静态水接触角的测量,发现其疏水性随p H升高而增大,体现出该纸基材料的p H响应特性.     

聚4-乙烯基吡啶原位修饰PVDF膜及其负载磷钨杂多酸催化剂的研究

以聚偏氟乙烯(polyvinylidene fluoride,PVDF)微滤膜为基膜,4-乙烯基吡啶(4-vinylpyridine,4VP)为功能单体,采用表面引发电子活化再生原子转移自由基聚合(SI-AGET ATRP)法在基膜表面原位改性,并通过接枝聚合物侧链上的吡啶基团与Keggin型磷钨杂多酸(H3PW12O40·n H2O,HPW)之间的静电作用,制备了新型混合催化膜.实验结果表明,接枝聚合过程表现出"活性"/可控表面引发接枝聚合性质,基膜表面接枝聚合物量随聚合反应时间呈现线性增加,当反应时间为16 h,聚合物接枝量达到2.25 mg/cm2,聚合物接枝量的增多致使其相互堆积并坍塌,造成膜表面出现块状聚集体.然后,利用溴代十六烷对接枝聚合物进行季铵化改性,制得表面含有吡啶鎓盐的阳离子复合膜,通过接枝聚合物侧基中的吡啶和吡啶鎓盐基团与磷钨杂多酸之间的静电作用促使其在改性膜表面上有效负载.负载后的磷钨杂多酸均匀的分布在膜表面及孔道中,并保持其化学结构.负载催化剂前后膜的接触角从80.4°减小到57.8°,体现了亲水性催化剂的负载对膜表面润湿性的显著影响.     

表面引发的原子转移自由基聚合法在聚偏二氟乙烯表面制备可控的聚甲基丙烯酸甲酯刷

采用表面引发的原子转移自由基聚合法(ATRP)在聚偏二氟乙烯(PVDF)表面制备结构可控的聚甲基丙烯酸甲酯刷。通过碱处理和紫外光照溴代的方法,将ATRP引入到PVDF表面; 然后采用ATRP法将甲基丙烯酸甲酯接枝到溴代的PVDF表面。采用傅里叶变换红外光谱和X-射线光电子能谱对改性前后PVDF表面的结构进行了表征。结果表明甲基丙烯酸甲酯成功地接枝到了PVDF表面。     

基于Diels-Alder反应与原子转移自由基聚合制备核壳型碳纳米管-笼型倍半硅氧烷杂化材料

通过糠醇与溴代异丁酰溴的酯化反应制备了溴代异丁酸呋喃甲酯,其与多壁碳纳米管(MWNT)发生Diels-Alder环加成反应得到了原子转移自由基聚合(ATRP)的引发剂(MWNT-Br),MWNT-Br通过ATRP反应引发了八丙烯酸酯基笼型倍半硅氧烷(POSS)的聚合,从而实现了POSS对多壁碳纳米管的包覆,通过对MWNT-Br中溴代异丁酸呋喃甲酯接枝量的控制,包覆POSS层的厚度可以从5 nm、10 nm到15 nm精确调节.     

结构规整的高密度两亲性接枝聚合物刷的合成及其自组装研究

大分子单体通过两种可控聚合方法, 即开环易位聚合(ROMP)和原子转移自由基聚合(ATRP)的联用, 合成一种新型两亲性接枝聚合物刷. 具有高环张力的降冰片烯单侧链大分子单体norbornene-graft-poly(ε-caprolactone)/Br (PCL- NBE-Br)首先进行ROMP反应, 生成聚合物主链, 每个单体单元上含有一条PCL链和一个溴官能团; 然后用含溴的ROMP聚合物poly(norbornene)-graft-poly(ε-caprolactone)/Br (PCL-PNBE-Br)作为大分子引发剂引发单体2-(dimethyl- amino)ethyl methacrylate)的ATRP反应, 生成结构明确的高密度两亲性接枝聚合物刷poly(norbornene)-graft-poly(ε- caprolactone)/poly(2-(dimethylamino)ethyl methacrylate) (PCL-PNBE-PDMAEMA), 其主链每个单体单元上均含有一条疏水性PCL接枝链和一条亲水性PDMAEMA接枝链. 最后, 研究此类高密度两亲性接枝聚合物刷的自组装行为, 用动态激光光散射(DLS)研究其在混合溶剂(THF/H2O)中的胶束行为, 考察胶束溶液的浓度以及不同长度的亲水性接枝链对胶束尺寸的影响; 利用透射电镜(TEM)观察胶束为球形, 具有类似线团或草莓状的形态.     

金表面聚合物刷及图案化微结构的制备

采用表面引发室温原子转移自由基聚合(ATRP)方法在金基底上原位制备了接枝聚合物刷，其制备过程用厚度测量，ATR-FTIR，XPS等进行了表征，初始时聚合物刷的厚度随着聚合时间的增加线性增加，表现为活性聚合的特征．XPS表征证明表面引发聚合后聚合物刷末端仍然存在ATRP反应的引发剂．紫外光刻图案化的聚合物刷作为电沉积的模板，经电沉积、后紫外处理、湿化学刻蚀步骤后得到了分离的导电聚合物微阵列结构，通过浇注／粘附处理将导电聚合物微阵列转移至硅油弹性体片，由于导电聚合物在湿化学刻蚀中对基底金具有良好的保护作用，因此在导电聚合物阵列被转移后，基底表面得到金微阵列。     

Controlled functionalization of multiwalled carbon nanotubes with various molecular-weight poly(L-lactic acid)

Multiwalled carbon nanotubes (MWNT) were functionalized with poly(L-lactic acid) (PLLA) with different molecular weights using a "grafting to" technique. The oxidized MWNT (MWNT-COOH) were converted to the acyl-chloride-functionalized MWNT (MWNT-COCl) by treating them with thionyl chloride (SOCl2) and reacting them with PLLA to prepare the MWNT-g-PLLA. FTIR and Raman spectroscopy revealed that the PLLA was covalently attached to the MWNT, and the weight gain due to the functionalization was determined by thermogravimetric analyses (TGA). The Raman signals of the MWNT were greatly weakened as a result of the PLLA grafting. The morphology of the grafted PLLA was examined by using SEM and TEM. The amount of grafted PLLA depended on the molecular weight of the PLLA. The PLLA coated on the MWNT became thicker and more uniform with increasing PLLA molecular weight from 1000 to 3000. However, the amount of grafted PLLA became lower when the molecular weight of PLLA was further increased to 11,000 and 15,000, and the PLLA attached to the MWNT showed a squid leglike morphology forming blobs and leaving much of the MWNT surface bare.     

电纺丝法制备聚乳酸/多壁碳纳米管/羟基磷灰石杂化纳米纤维的研究

电纺丝是一种利用聚合物溶液或熔体在强电场中进行喷射纺丝的加工技术,所制得的纤维、直径一般在数十纳米至几微米之间,比传统方法制得的纤维直径小几个数量级,是获得纳米尺寸长纤维的有效方法之一．     

Covalent assembly and micropatterning of functionalized multiwalled carbon nanotubes to monolayer-modified Si(111) surfaces

Multiwalled carbon nanotubes (MWNTs) covalently bound to monocrystalline p-type Si(111) surfaces have been prepared by attaching soluble amine-functionalized MWNTs onto a preassembled undecanoic acid monolayer using carbodiimide coupling. SEM analysis of these functionalized surfaces shows that the bound MWNTs are parallel to the surface rather than perpendicular. The voltammetric and electrochemical impedance spectroscopy measurements reveal that the electron transfer at the MWNT-modified surface is faster than that observed at a MWNT-free alkyl monolayer. We have also demonstrated that it is possible to prepare MWNT micropatterns using this surface amidation reaction and a "reagentless" UV photolithography technique. Following this approach, MWNT patterns surrounded by n-dodecyl areas have been produced and the local electrochemical properties of these micropatterned surfaces have been examined by scanning electrochemical microscopy. In particular, it is demonstrated that the MWNT patterns allow a faster charge transfer which is consistent with the results obtained for the uniformly modified surfaces.     

聚氨酯接枝多壁碳纳米管的制备及表征

采用两步法成功地将聚氨酯分子链以共价键连接到碳纳米管表面. 首先将聚丙烯酰氯通过与强酸氧化后多壁碳纳米管表面产生的羟基及少量羧基之间的化学反应共价接枝到碳纳米管表面; 然后将接枝到碳纳米管表面的聚丙烯酰氯与端羟基聚氨酯发生酯化反应, 实现了聚氨酯对碳纳米管的表面共价接枝. 采用傅里叶变换红外光谱(FTIR)、透射电镜(TEM)、扫描电镜(SEM) 和热重分析(TGA)等对接枝后的产物进行了表征, 结果表明, 聚氨酯已共价接枝到碳纳米管表面, 被接枝的聚合物的含量接近90%.     

聚丙烯酸功能化多壁碳纳米管

Covalent functionalization of multiwalled carbon nanotubes （MWNT） with poly（acrylic acid） has been successfully achieved via grafting of poly（acryloyl chloride） on nanotube surface by esterification reaction of acyl chloride-bound polymer with hydroxyl functional groups present on acid-oxidized MWNT and hydrolysis of polymer attached to nanotubes. Polymer-functionalized MWNT could possess remarkably high solubility in water, and their aqueous solution was very stable without any observable black deposit for a long time. Characterizations of such functionalized MWNT samples using Fourier transform infrared spectrometer, transmission electron microscopy and nuclear magnetic resonance techniques indicated that poly（acrylic acid） was covalently attached to the surface of MWNT.     

Melt mixing of polycarbonate with multiwalled carbon nanotubes: microscopic studies on the state of dispersion

The focus of the paper is to investigate several issues related to the state of dispersion of multiwalled carbon nanotubes (MWNTs) in a polycarbonate (PC) matrix. A masterbatch of PC-MWNT (15 wt.%) was diluted with different amounts of PC in a small scale conical twin screw extruder (DACA Micro Compounder) to obtain different compositions of MWNT. In this system, electrical measurements indicated percolation of MWNT between 1.0 and 1.5 wt.%. We report TEM and AFM investigations of the state of dispersion of MWNT, in the entire volume of the matrix, in selected composites with compositions below (1 wt.% MWNT) and above the percolation threshold (2 and 5 wt.% MWNT). In addition, it was investigated if surface segregation of MWNT and flow induced orientation of nanotubes within the extruded strands had been occurred. It is found that the nanotubes dispersed uniformly through the matrix showing no significant agglomeration in the compositions studied. TEM micrographs seem to be able to detect the percolated structure of the carbon nanotubes. Furthermore, by comparing AFM micrographs from the core region and near to surface region no evidence of segregation or depletion of MWNT at the surface of the extruded strand was found. Comparison of TEM and AFM micrographs on surfaces cut along and perpendicular to the strand direction led to the conclusion that no preferred alignment had occurred as a result of extrusion. Aside from TEM technique, AFM is shown to be suitable to characterize the state of nanotube dispersion along with the issue of surface segregation and orientation of the nanotubes.     

纳米碳管电极上氧的电催化还原

以聚四氟乙烯为粘结剂制成了多壁纳米碳管（MWNT）电极.采用恒电位阶跃法和循环伏安法研究了MWNT电极在碱性溶液中的电化学行为，并对碱性溶液中溶解氧在该电极上的电化学还原行为进行了研究.实验结果表明： MWNT电极具有比石墨电极更高的孔隙率和电化学表面积；MWNT电极上O2还原成的反应为准可逆过程；在5～50 mV•s－1的扫描速率范围内，阴极峰电流与扫描速度成线性关系，表明MWNT电极上O2还原成的反应受吸附控制；对碱性溶液中的氧还原反应， MWNT比石墨具有更高的催化活性.     

Preparation and electrochemical properties of MnO2 nanosheets attached to Au nanoparticles on carbon nanotubes

A wet chemical route for the preparation of MnO(2) nanosheet/Au nanoparticle/MWNT hybrid materials is developed. The Au nanoparticles are prepared by reducing AuCl(4)(-) with citrate and attached to thiol-modified MWNTs. Owing to the reducing property and the binding ability to Mn-containing species of capping agents surrounded the Au nanoparticles, the MnO(2) nanosheets are formed on the surface of Au nanoparticles. The ternary nanocomposites of MnO(2)/Au/MWNT have been characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and FT-IR spectroscopy. The affiliation of MnO(2) nanosheets into the hybrids remarkably enhances the electrocatalytic performance of Au nanoparticle/MWNT towards the oxygen reduction reaction. The specific capacitance of the ternary hybrids is also increased dramatically comparing with that of Au/MWNT.     

多壁碳纳米管固相萃取填料对芳香化合物的吸附机理研究

研究了多壁碳纳米管(MWNT)作为固相萃取柱填料对芳香有机化合物的吸附性能,并探讨了吸附作用的本质。采用MWNT分别萃取了不同结构的物质,实验结果表明,MWNT对芳香有机化合物有较强的吸附作用,这种作用主要是由于MWNT表面的离域大π键和芳香环的共轭π键相互作用的结果,而碳纳米管的高比表面积产生的物理吸附作用相对要小得多。     

Enhanced Electrocatalysis for the Reduction of Hydrogen Peroxide at New Multiwall Carbon Nanotube Grafted Polydiphenylamine Modified Electrode

A new modified electrode having multiwall carbon nanotube (MWNT) grafted with polydiphenylamine (PDPA) as electrocatalytic layer is fabricated. FESEM image of the modified electrode shows a different morphology indicating the grafting of PDPA over MWNT. This morphology is in quite contrast from the conventional bilayer MWNT/conducting polymer modified electrode. The multiwall carbon nanotube grafted polydiphenylamine (MWNT‐g‐PDPA‐ME) shows excellent electrocatalytic activity towards the reduction of hydrogen peroxide. The combined presence of MWNT and PDPA as a single unit provides better sensitivity than the bilayer configuration (MWNT/PDPA‐ME). This modified electrode shows accelerated electron transfer at the interface with minimized surface fouling and surface renewability. The advantages of MWNT‐g‐PDPA‐ME over the bilayer electrode are demonstrated with chronoamperometric studies. The amperometric response to H₂O₂ obtained at ?300 mV (vs. SCE) is rapid and highly sensitive as evident from the higher (2.83×10^?3 cm³ mol^?1 s^?1) rate constant for the diffusion reduction process.