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published in(发表于) 2013/3/21 6:58:46
China's zhejiang university to create the world's most light material

China's zhejiang university to create the world's most light material
SCI-TECH-FRONT Xinhuanet Jian-Bin Yu Zhou Hui 2013-03-21 10:39
ZheJiang university professor department of polymer science GaoChao professor Made group produced a kind of super light aerogel, which refreshed the record of the most lightweight materials in the world today, elasticity and oil absorption capacity to surprise. This is referred to as "the carbon aerogel" of solid material density of 0.16 milligrams per cubic centimeter, is only 1/6 of the air density (note: tencent science such as according to the air in a standard atmospheric pressure, density under the condition of 25 ℃ ambient temperature is 1.18 mg per cubic cm calculation, it should be 1/7 of the air density is relatively appropriate; according to the density of air at 0 ℃ condition is 1.29 mg per cubic cm calculation, it should be for 1/8 of the air density is more appropriate. Recently, the development by the journal nature, the key figure captions under the "news" section.
According to introducing, aerogel is included in the guinness book of world records the lightest of substances, due to its internal has many pores, is filled with air, so its name. In 1931, the American scientists using silica aerogel was the earliest, the nickname "frozen smoke". In 2011, the United States at HRL laboratories, the university of California, irvine, and the California institute of technology cooperation of preparing a nickel aerogel, density of 0.9 mg/cubic centimeters, hit a record at the time the lightest material. This material on the dandelion flowers, soft fluffy little deformation, the photo included in the annual 10 images of nature, also left a deep impression to superb: a kind of material can, challenge the limit?
Graphite reserves are abundant in our country, accounts for two-thirds of the world. Scientists have been exploring the method of efficient utilization of graphite. "Graphite into graphene (by a monolayer of carbon atoms lamellar structure), its value can rise thousands of times." Excellent team after five or six years of exploration, preparation of the one-dimensional and two-dimensional graphene fiber graphene films. This time, they are going to make graphene into a three-dimensional porous materials to hit a record.
Make simple
Shape, size can be adjusted, and large-scale production as possible
In laboratory, the reporter saw the small sizes of carbon sponges: they big such as tennis, small such as the bottle stopper. Under the electron microscope, carbon nanotubes, and graphene common supporting numerous pores.
"Like sports venues and other large space structure, made from steel bracket, made of high strength thin films such as walls, material as a whole is both light and strong." Research doctoral Sun Haiyan said, "here, the carbon nanotube is support, graphene is wall."
In the reported results, excellent team preparation of "carbon sponge" is still the most lightweight record-holder -- can be up to 0.16 mg/cubic centimeters, below the helium gas density. Relevant papers published online Feb. 18 in the journal advanced materials. But not much research interest in declaration of the guinness book of world records, "" light" is not its biggest new idea ". Excellent explanation: its value lies in its simple preparation method, and the materials exhibit superior performance.
Scientists say, is the basic principle of preparation of aerogel to remove solvent in the gel, let it keep a complete skeleton. Preparation of aerogels in previous cases, scientists mainly adopts sol - gel method and template orientation method. The former can batch synthesis, but poor controllability; The latter can produce orderly structure, but depends on the template of the fine structure and size, to a lot of preparation. Excellent team to explore no template freeze drying: will dissolve the graphene and carbon nanotubes in aqueous solution at low temperature freezing and drying, and won the "carbon" sponge, and the shape can be arbitrary regulation, make the production process more convenient, also make the mass production of lightweight materials and application possible.
"Don't need a template, only related to the container. The container how much, how can preparation, can do thousands of cubic centimeter, or even more." GaoChao said.
Superior Performance
High elastic, strong adsorption, broad application prospects
The title of the review is in nature magazine: Solid carbon: elastic and lightsome: Think that the performance of a new surprise.
According to introducing, "sponge" carbon has high flexibility, can still be restorable after being compressed 80%. Its adsorption of organic solvent with super fast, high force, is the oil suction force has been reported the highest material. Oil absorption of the existing product normally only about 10 times the mass of the liquid suction itself, and the absorption of carbon foam is about 250 times, of up to 900 times, and oil absorption does not bibulous. "Big stomach king" extremely fast to eat organic: such a "carbon sponge" per gram per second can absorb 68.8 grams of organic matter. It makes people think of use it to deal with Marine oil spill, "can put them on the sea, can make the oil absorb quickly, because there are elastic, suction pressure oil can be recycled, 'carbon sponges can also be use again." Researchers said.
At present, the laboratory is on the adsorption performance of the material was further applied research. Researchers said that "carbon sponge" may also be the ideal phase change energy storage heat preservation material, catalytic carrier, sound-absorbing materials and efficient composite materials. However, this new material as the baby is born, scientists are also difficult to predict its application area and prospect, still have to rely on the imagination of the society and industry, make this new materials out of the lab and realize the value of application.
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中国浙江大学制造出世界最轻材料
科技前沿 新华网 余建斌 周炜 2013-03-21 10:39
浙江大学高分子系高超教授的课题组制备出了一种超轻气凝胶——它刷新了目前世界上最轻材料的纪录，弹性和吸油能力令人惊喜。这种被称为“全碳气凝胶”的固态材料密度为每立方厘米0.16毫克，仅是空气密度的1/6【腾讯科学注：如根据空气在一个标准大气压、25℃室温条件下密度是每立方厘米1.18毫克计算，这里应该为空气密度的1/7较合适；如根据空气在0℃条件下密度是每立方厘米1.29毫克计算，这里应该为空气密度的1/8较合适】。日前，这一进展被《自然》杂志在“研究要闻”栏目中重点配图评论。
据介绍，气凝胶是入选吉尼斯世界纪录的最轻的一类物质，因其内部有很多孔隙，充斥着空气，故而得名。1931年，美国科学家用二氧化硅制得了最早的气凝胶，外号 “凝固的烟”。2011年，美国HRL实验室、加州大学欧文分校和加州理工学院合作制备了一种镍构成的气凝胶，密度为0.9毫克/立方厘米，创下了当时最轻材料的纪录。把这种材料放在蒲公英花朵上，柔软的绒毛几乎没有变形——这张照片入选了《自然》杂志年度十大图片，也给高超留下了深刻印象：能不能制备出一种材料，挑战这个极限？
我国的石墨储备非常丰富，占全世界的2/3。科学家一直在探索石墨高效利用的方法。“把石墨变成石墨烯（一种由碳原子构成的单层片状结构），其价值可以上升数千倍。”高超的课题组经过五六年的探索，制备出了一维的石墨烯纤维和二维的石墨烯薄膜。这次，他们打算把石墨烯做成三维多孔材料来冲击这一纪录。
制作简便
形状、尺寸可任意调节，大规模制造成可能
在实验室，记者看到了一个个大小不等的“碳海绵”：它们大的如网球，小的如酒瓶塞。在电子显微镜下，碳纳米管和石墨烯共同支撑起无数个孔隙。
“就像体育场馆等大型空间结构，用钢筋做支架，用高强度的薄膜等做墙壁，材料整体既轻且强。”课题组博士生孙海燕说，“在这里，碳纳米管就是支架，石墨烯就是墙壁。”
在已报道的成果中，高超课题组制备的“碳海绵”仍是最轻纪录保持者——可达到0.16毫克/立方厘米，低于氦气的密度。相关论文2月18日在线发表在《先进材料》上。但课题组对申报吉尼斯世界纪录兴趣不大，“‘轻’并不是它最大的新意所在”。高超解释：它的价值在于其简便的制备方法，以及材料所展现出来的优越性能。
科学家介绍说，气凝胶的基本制备原理是除去凝胶中的溶剂，让其保留完整的骨架。在以往制备气凝胶的案例中，科学家主要采用溶胶—凝胶法和模板导向法。前者可以批量合成，但是可控性差；后者能产生有序的结构，但依赖于模板的精细结构和尺寸，难以大量制备。高超课题组另辟蹊径，探索出无模板冷冻干燥法：将溶解了石墨烯和碳纳米管的水溶液在低温下冻干，便获得了“碳海绵”，并且可以任意调节形状，令生产过程更加便捷，也使这种超轻材料的大规模制造和应用成为可能。
“不需要模板，只与容器有关。容器多大，就可以制备多大，可以做到上千立方厘米，甚至更大。”高超说。
性能优越
高弹性、强吸附，应用前景广阔
《自然》杂志点评的标题是：《固体碳：弹性而轻盈》，认为这一新生事物的性能令人惊喜。
据介绍，“碳海绵”具备高弹性，被压缩80%后仍可恢复原状。它对有机溶剂具有超快、超高的吸附力，是迄今已报道的吸油力最高的材料。现有的吸油产品一般只能吸自身质量10倍左右的液体，而“碳海绵”的吸收量是250倍左右，最高可达900倍，而且只吸油不吸水。“大胃王”吃有机物的速度极快：每克这样的“碳海绵”每秒可以吸收68.8克有机物。这让人想到用它来处理海上的漏油，“可以把它们撒在海面上，就能把漏油迅速地吸收进来，因为有弹性，吸的油能够被压出来回收利用，‘碳海绵’也可以重新使用。”科研人员表示。
目前，实验室正在对这一材料的吸附性能进行进一步的应用性研究。科研人员说，“碳海绵”还可能成为理想的相变储能保温材料、催化载体、吸音材料以及高效复合材料。不过，这一新生材料就如呱呱坠地的婴儿，科学家还很难准确预计其应用领域与前景，还得依靠社会以及产业界的想象力，让这个新材料走出实验室，实现应用价值。
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