Polyaniline/Ag Composite Nanotubes Prepared through UV Rays Irradiation via Fiber Template Approach and their NH3 Gas Sensitivity
Polyaniline/Ag Composite Nanotubes Prepared through UV Rays Irradiation via Fiber Template Approach and their NH3 Gas Sensitivity
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DOI：
10.1021/jp0762727
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发表时间：
2009-01-08
影响因子：
3.7
通讯作者：
Qu, Lunyu
中科院分区：
文献类型：
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作者：
Li, Xia;Gao, Yu;Qu, Lunyu
以聚环氧乙烷-b-聚环氧丙烷-b-聚环氧乙烷（Pluronic F127）和聚4-羟基苯乙烯（PHOSt）为模板，通过正硅酸乙酯在模板中的气相缩合反应制备了有序介孔膜。通过改变模板膜中的Pluronic F127：PHOSt的比例，可以调整合成的介孔二氧化硅的长程有序性，在约15重量% PHOSt下观察到最大的晶粒。中孔的有序性和取向的这种增加伴随着孔径分布的变窄、平均中孔半径的略微增加和膜的杨氏模量的大幅增加。从该15wt%PHOSt组合物到更高或更低的PHOSt负载的偏差导致长程有序的衰减和随后的膜模量的降低。通过PHOSt浓度（1- 50wt%）的改性对机械性能的调节接近1个数量级，而不显著改变孔隙率。此外，通过TEM显微照片测定的具有几乎不可区分的形态的样品可以表现出3倍的模量差异。以合适的纤维为模板，分别以H_4SiW_（12）O_（40）（SiW_（12））和银银（AgNO_3）为掺杂剂和氧化剂，成功地制备了聚苯胺（PANI）/Ag复合纳米管。银纳米粒子在聚苯胺纳米管中的分散非常均匀。通过红外光谱（FT-IR）、X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）对产物的结构和形貌进行了表征。紫外线在聚合反应中起重要作用。提出了PANI/Ag复合纳米管的可能形成机理。PANI/Ag复合纳米管的平均内径为170 nm，与模板的直径一致。PANI/Ag复合纳米管的高比表面积、小直径和多孔性质在气敏性和时间响应性方面都有明显的改善。此外，在有机膜中引入金属有效地提高了化学电阻器对NH3的灵敏度。在室温下考察了对NH_3气体的气敏特性。同时，PANI/Ag复合纳米管的可逆循环响应变化具有合理的重现性，在传感器开发领域具有更大的应用潜力。
Ordered mesoporous films are synthesized from the vapor-phase condensation of tetraethyl orthosilicate within preformed amphiphilic template films consisting of a blend of poly(ethylene oxide)-b-poly(propylene oxide)b-poly(ethylene oxide) (Pluronic F127) and poly(4-hydroxystyrene) (PHOSt). By modification of the Pluronic F127:PHOSt ratio in the template film, the long range order of the synthesized mesoporous silica can be tuned with the largest grains observed at approximately 15 wt % PHOSt. This increase in ordering and orientation of the mesopores is accompanied by a narrowing of the pore size distribution, a slight increase in the average mesopore radius, and a substantial increase in the Young's modulus of the film. Deviations from this 15 wt % PHOSt composition to higher or lower PHOSt loadings result in a decay in the long range ordering and subsequently a decrease in the film modulus. The modulation in the mechanical properties through modification in the PHOSt concentration (1-50 wt %) is nearly I order of magnitude without significantly altering the porosity. Moreover, samples with nearly indistinguishable morphology as determined through TEM micrographs can exhibit a difference in modulus by a factor of 3. This work demonstrates the importance of long range order for fabricating mechanically robust porous films.Polyaniline(PANI)/Ag composite nanotubes have been Successfully prepared using a suitable fiber as template in the presence of H4SiW12O40 (SiW12) and silver nitrate (AgNO3) as a dopant and an oxidant, respectively. The Ag nanoparticles dispersed in the PANI nanotubes are very uniform. The structure and morphology of the product are characterized by Fourier transform infrared (FT-IR) spectrum, X-ray diffraction (XRD) pattern, scanning electron microscope (SEM), and transmission electron microscopy (TEM) images. UV rays play an important role in the polymerization. A potential formation mechanism of the PANI/Ag composite nanotubes is suggested. The average inner diameter of PANI/Ag composite nanotubes is 170 nm, which is consistent with the diameter of the template. The high Surface areas, small diameter, and porous nature of the PANI/Ag composite nanotubes give significantly better performance in both gas sensitivity and time response. Moreover, the introduction of metal into organic films is effective in promoting the chemiresistor sensitivity to NH3. The gas-response to NH3 gas is examined at room temperature. Meanwhile, the reversible circulation response change of PANI/Ag composite nanotubes has a reasonable reproducibility and has more potential applications in the area of sensor development.