中國時報 F2/國際新聞 2007/10/06
超級塑膠 薄如紙 硬如鋼
【潘勛�法新社芝加哥四日電】
美國密西根大學科學團隊已造出一種透明的新塑膠，強度硬如鋼鐵，卻薄得像一張紙，這種新塑膠可望在1、2年內商業化。
要使用只有奈米大小的「建築砌塊」，造出複合材料，既維持材料的強度又兼顧到大小，向來是科學家頭痛的難題。密西根團隊的主任柯托夫表示，他們成功造出這種新塑膠的方法，是模擬海貝的分子結構，就像砌磚時在磚塊之間塗灰泥，把奈米薄膜當成磚，以交錯的形式疊起來，每一層之間再添加黏膠似的聚合物，以產生氫原子的連結。
柯托夫表示，這種塑膠的原始奈米薄膜是由黏土造出來的，而加以黏合的聚合物則很像學生用的黏膠，沒有毒性。此外，這種複合塑膠可以自然分解，只要很少的能源就可以造出來，十分環保。
此外，這種塑膠可以運用在化學工廠，減少分離各類氣體時消耗的 能源；也可以改善微型科技，比如微晶片、生物醫學感測器。有朝一日甚至可以用來製造更輕更強的裝甲，供軍警人員及車輛使用。
科托夫已著手研究這種複合塑膠的應用方法，他表示，雖然還在探索階段，但他們實驗室裡正在建造機器，將來可以造出每張1平方公尺見方的這種塑膠。
超級塑膠 薄如紙 硬如鋼
Transparent Plastic Polymer is Strong as Steel
Researchers invent nanosheet polymer that is transparent and as strong as steel
If Star Trek and Wonder Woman were any indicators, high-strength transparent materials have been the stuff of science fiction for decades. If researchers at the University of Michigan have anything to say about it, new transparent materials will become a reality very soon.
Researcher Nicolas Kotov considered dubbing the material 「Plastic Steel」 but decided the material was not pliable enough for the moniker.
The new material is constructed from layers of clay nano-sheets and a water-soluble polymer that shares similar chemistry with ordinary white glue. A paper on the new composite material was authored by Kotov and other University of Michigan faculty members for the October 5 edition of Science.
The material was created using a machine developed to build materials one nano-layer after another. A robotic arm hovers over a wheel of vials of different liquids. The arm takes a piece of glass the size of a stick of gum and dips it into the polymer glue material and then into a liquid containing a dispersion of clay nanosheets. After the layers dry, the process is repeated until 300 layers of the polymer glue and clay nono-sheets form a super-strong transparent substrate.
That process created a piece of the material about as thick as a piece of plastic wrap. Researchers say that one of the reasons the material is so strong is that it uses a Velcro Effect. The Velcro Effect allows bonds within the sheet that are broken to be reformed easily in a new place.
Researchers also claim to have increased the strength of the material by offsetting the seams of the layers -- similar to the way a bricklayer offsets bricks in a wall.
The material is currently being investigated for possible applications in aviation. Cosmos Magazine quotes Kotov as saying, "We're still at the exploratory stage but the machine is now being built in our lab to build piece as big as one meter by one meter."
Researchers invent nanosheet polymer that is transparent and as strong as steel
If Star Trek and Wonder Woman were any indicators, high-strength transparent materials have been the stuff of science fiction for decades. If researchers at the University of Michigan have anything to say about it, new transparent materials will become a reality very soon.
Researcher Nicolas Kotov considered dubbing the material 「Plastic Steel」 but decided the material was not pliable enough for the moniker.
The new material is constructed from layers of clay nano-sheets and a water-soluble polymer that shares similar chemistry with ordinary white glue. A paper on the new composite material was authored by Kotov and other University of Michigan faculty members for the October 5 edition of Science.
The material was created using a machine developed to build materials one nano-layer after another. A robotic arm hovers over a wheel of vials of different liquids. The arm takes a piece of glass the size of a stick of gum and dips it into the polymer glue material and then into a liquid containing a dispersion of clay nanosheets. After the layers dry, the process is repeated until 300 layers of the polymer glue and clay nono-sheets form a super-strong transparent substrate.
That process created a piece of the material about as thick as a piece of plastic wrap. Researchers say that one of the reasons the material is so strong is that it uses a Velcro Effect. The Velcro Effect allows bonds within the sheet that are broken to be reformed easily in a new place.
Researchers also claim to have increased the strength of the material by offsetting the seams of the layers -- similar to the way a bricklayer offsets bricks in a wall.
The material is currently being investigated for possible applications in aviation. Cosmos Magazine quotes Kotov as saying, "We're still at the exploratory stage but the machine is now being built in our lab to build piece as big as one meter by one meter."
New Plastic Is Strong As Steel, Transparent
Science Daily — By mimicking a brick-and-mortar molecular structure found in seashells, University of Michigan researchers created a composite plastic that's as strong as steel but lighter and transparent.
It's made of layers of clay nanosheets and a water-soluble polymer that shares chemistry with white glue.
Engineering professor Nicholas Kotov almost dubbed it "plastic steel," but the new material isn't quite stretchy enough to earn that name. Nevertheless, he says its further development could lead to lighter, stronger armor for soldiers or police and their vehicles. It could also be used in microelectromechanical devices, microfluidics, biomedical sensors and valves and unmanned aircraft.
Kotov and other U-M faculty members are authors of a paper on this composite material, "Ultrastrong and Stiff Layered Polymer Nanocomposites," published in the Oct. 5 edition of Science.
The scientists solved a problem that has confounded engineers and scientists for decades: Individual nano-size building blocks such as nanotubes, nanosheets and nanorods are ultrastrong. But larger materials made out of bonded nano-size building blocks were comparatively weak. Until now.
"When you tried to build something you can hold in your arms, scientists had difficulties transferring the strength of individual nanosheets or nanotubes to the entire material," Kotov said. "We've demonstrated that one can achieve almost ideal transfer of stress between nanosheets and a polymer matrix."
The researchers created this new composite plastic with a machine they developed that builds materials one nanoscale layer after another.
The robotic machine consists of an arm that hovers over a wheel of vials of different liquids. In this case, the arm held a piece of glass about the size of a stick of gum on which it built the new material.
The arm dipped the glass into the glue-like polymer solution and then into a liquid that was a dispersion of clay nanosheets. After those layers dried, the process repeated. It took 300 layers of each the glue-like polymer and the clay nanosheets to create a piece of this material as thick as a piece of plastic wrap.
Mother of pearl, the iridescent lining of mussel and oyster shells, is built layer-by-layer like this. It's one of the toughest natural mineral-based materials.
The glue-like polymer used in this experiment, which is polyvinyl alcohol, was as important as the layer-by-layer assembly process. The structure of the "nanoglue" and the clay nanosheets allowed the layers to form cooperative hydrogen bonds, which gives rise to what Kotov called "the Velcro effect." Such bonds, if broken, can reform easily in a new place.
The Velcro effect is one reason the material is so strong. Another is the arrangement of the nanosheets. They're stacked like bricks, in an alternating pattern.
"When you have a brick-and-mortar structure, any cracks are blunted by each interface," Kotov explained. "It's hard to replicate with nanoscale building blocks on a large scale, but that's what we've achieved."
Collaborators include: mechanical engineering professor Ellen Arruda; aerospace engineering professor Anthony Waas; chemical, materials science and biomedical engineering professor Joerg Lahann; and chemistry professor Ayyalusamy Ramamoorthy. Kotov is a professor of chemical engineering, materials science and engineering, and biomedical engineering.
The nanomechanical behavior of these materials is being modeled by professor Arruda's group; Waas and his group are working on applications in aviation.
Note: This story has been adapted from material provided by University of Michigan.
Science Daily — By mimicking a brick-and-mortar molecular structure found in seashells, University of Michigan researchers created a composite plastic that's as strong as steel but lighter and transparent.
It's made of layers of clay nanosheets and a water-soluble polymer that shares chemistry with white glue.
Engineering professor Nicholas Kotov almost dubbed it "plastic steel," but the new material isn't quite stretchy enough to earn that name. Nevertheless, he says its further development could lead to lighter, stronger armor for soldiers or police and their vehicles. It could also be used in microelectromechanical devices, microfluidics, biomedical sensors and valves and unmanned aircraft.
Kotov and other U-M faculty members are authors of a paper on this composite material, "Ultrastrong and Stiff Layered Polymer Nanocomposites," published in the Oct. 5 edition of Science.
The scientists solved a problem that has confounded engineers and scientists for decades: Individual nano-size building blocks such as nanotubes, nanosheets and nanorods are ultrastrong. But larger materials made out of bonded nano-size building blocks were comparatively weak. Until now.
"When you tried to build something you can hold in your arms, scientists had difficulties transferring the strength of individual nanosheets or nanotubes to the entire material," Kotov said. "We've demonstrated that one can achieve almost ideal transfer of stress between nanosheets and a polymer matrix."
The researchers created this new composite plastic with a machine they developed that builds materials one nanoscale layer after another.
The robotic machine consists of an arm that hovers over a wheel of vials of different liquids. In this case, the arm held a piece of glass about the size of a stick of gum on which it built the new material.
The arm dipped the glass into the glue-like polymer solution and then into a liquid that was a dispersion of clay nanosheets. After those layers dried, the process repeated. It took 300 layers of each the glue-like polymer and the clay nanosheets to create a piece of this material as thick as a piece of plastic wrap.
Mother of pearl, the iridescent lining of mussel and oyster shells, is built layer-by-layer like this. It's one of the toughest natural mineral-based materials.
The glue-like polymer used in this experiment, which is polyvinyl alcohol, was as important as the layer-by-layer assembly process. The structure of the "nanoglue" and the clay nanosheets allowed the layers to form cooperative hydrogen bonds, which gives rise to what Kotov called "the Velcro effect." Such bonds, if broken, can reform easily in a new place.
The Velcro effect is one reason the material is so strong. Another is the arrangement of the nanosheets. They're stacked like bricks, in an alternating pattern.
"When you have a brick-and-mortar structure, any cracks are blunted by each interface," Kotov explained. "It's hard to replicate with nanoscale building blocks on a large scale, but that's what we've achieved."
Collaborators include: mechanical engineering professor Ellen Arruda; aerospace engineering professor Anthony Waas; chemical, materials science and biomedical engineering professor Joerg Lahann; and chemistry professor Ayyalusamy Ramamoorthy. Kotov is a professor of chemical engineering, materials science and engineering, and biomedical engineering.
The nanomechanical behavior of these materials is being modeled by professor Arruda's group; Waas and his group are working on applications in aviation.
Note: This story has been adapted from material provided by University of Michigan.