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nanosurface 2007-05-28 21:44

纳米陶瓷纖維問世

[b]美國與西班牙科學家利用「激光紡絲」(laser spinning)新技術，紡出長數公分且寬僅35 nm之非晶型纳米纖維(nanofiber)。這項突破使研究人員有能力製作幾近連續的纖維(near-continuous fibres)，而且還可以事先調配其化學成份。[/b]4_o%`S9Z
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纳米線(nanowires)、纳米帶(nanobelts)、纳米棒(nanorods)以及纳米管(nanotubes)等準一維 (quasi-one-dimensional)結構皆有著獨特的電性與機械性質，可望應用在電子、觸媒、偵測器、複合材料及生物醫學等眾多領域。目前這些結構多半是利用氣相(vapour phase)或以溶液為主(solution-based)成長法製作，雖然科學家想將這些材料製成纳米級的連續纖維，但目僅能使用幾種拉伸熔融前驅材料 (precursor material)的技術，製造出微米級的纖維。~,cn)S4jgF,g*A

@8C&o Ps 最近，這個問題已經被Vigo大學的Juan Pouand與Rutgers大學的Adrian Mann等人克服。他們利用簡單的物理方法製作出非常長的非晶型纳米纖維，而且除了前驅體材料外，不需要使用觸媒、模板及其他試劑。此方法不僅可以製造出纳米級的纖維，還可以將其他技術(如電紡法(electrospinning))無法處理的高熔點材料，直接製成纳米纖維。"Ud0QT0C2J9P

tp$g;y'|R4} 雷射紡絲法主要是以高功率雷射切入陶瓷材料前趨體(如二氧化矽或氧化鋁)平板，這種作法可確保的任何時刻都只有少量陶瓷處於熔融流體狀態。接著，以超音速噴嘴(supersonic nozzle)將高速氣體注入熔融區，黏稠的熔融材料在簡單的拉伸過程中藉由噴氣快速冷卻，產生一個非晶體微纳米纖維糾結成的網狀結構。5]%|k,RB

A x8cf Rc.x 研究人員指出，這項利用物理而非化學的技術可以製作出非常長且成份經設計的非晶型纳米纖維，可能的應用包括纳米複合材料、纳米模版(nano- templating)、組織工程(tissue engineering)、感測器及新型織物。目前該團隊正著手改善製程的控制，並製作新的複合材料。詳見近期的Applied Physics Letters。
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zF'[#n/q;H 原始網站: [url]http://nanotechweb.org/articles/news/6/4/19/1[/url]
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9l3n2zB2wx `|)H:K.t 譯者:黃振瑋(逢甲大學纖維與複合材料學系)
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[quote]
ZZ k t8vk4kt^ [b][size=4]Ceramic fibres reach the nanoscale
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+[C br#Z9k [/size][/b][b]Material scientists in the US and Spain have invented a new technique called "laser spinning" to produce very long amorphous nanofibres that are several centimetres long, but just 35 nm across. The breakthrough advance could allow near-continuous fibres with tailored compositions to be made.[/b]
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$W`(a[ M!|MX Quasi-one-dimensional structures such as nanowires, nanobelts, nanorods and nanotubes have unique electrical and mechanical properties. They look set to revolutionize fields as diverse as electronics, catalysis, sensing, composite materials and biomedicine. At present, these structures are typically produced by vapour phase or solution-based growth. Scientists would also like to make continuous lengths of these materials on the nanoscale, as this would be a major technical and economic advance. However, at present they are only able to produce micron-sized fibres using several techniques that rely on elongating a molten viscous batch of precursor material.
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+dx \N-O3]gt I [i]Micrographs showing the typical appearance of laser spun fibres. (a) Overall view of an as-produced mesh of fibres (field emission scanning electron microscopy image). This shows a mixture of long micrometric fibres and nanofibres. (b) Transmission electron microscopy image of a single nanofibre with a diameter of approximately 50 nm. The inset diffraction pattern shows its amorphous structure (image and text: Appl. Phys. Lett.).[/i]xMP%XK-o&T

Z(]``fI p?Z0r Juan Pou and colleagues at the University of Vigo and Adrian Mann and co-workers at Rutgers University have now overcome this problem. The researchers have produced very long amorphous nanofibres in a simple physical process that does not involve catalysts, templates or any other reagents except the precursor material with the desired fibre composition. Not only does the method produce nanosized fibres, it can also produce nanofibres directly from materials that melt at high temperatures – something that is not possible with other similar techniques, such as electrospinning.
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[i]Photo courtesy: F Quintero[/i]
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Laser spinning essentially involves using a high-power laser to make a cut in a plate of the precursor ceramic material, such as silica or alumina. This novel approach ensures that only a small volume of ceramic is in the fluid state – at the melt front (the leading edge of the cut) – at any one time. While this is being done, a supersonic nozzle injects a high-velocity gas jet in the area of the cut. The viscous molten material produced is then quickly stretched and cooled by the gas jet in a simple elongation process, to yield a disordered net of intertwined amorphous micro- and nano-fibres (see figure).9Uv$Y:q5c Z2G,Y'W
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"This advance is exciting because the physical (rather than chemical) nature of this technique allows the production of very long amorphous nanofibres with tailored compositions," lead author Félix Quintero told nanotechweb.org. "Some likely applications of these nanofibres include nanocomposites, nano-templating, tissue engineering, sensors, and new types of fabrics."
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#P+j7c ?h]!hz The team is now working on better controlling the process and making new compositions.(m Ay/nU
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The work was published in [url=http://scitation.aip.org/journals/doc/APPLAB-ft/vol_90/iss_15/153109_1.html][i]Appl. Phys. Lett.[/i] [b] 90[/b] 153109[/url].
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R K2[7b0cED [[i] 本帖最后由 nanosurface 于 2007-05-28 08:46 编辑 [/i]]

wendy_lyw 2008-06-29 00:12

呃。。只知道可以用电纺制备纳米陶瓷纤维，貌似Li Dan他们做了很多这方面的工作
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