Professor Gao Chao.
The nano-polymer research group of polymer department of Zhejiang University is led by Professor Gao Chao, winner of the National Outstanding Youth Fund. At present, the research group consists of professors 1 person, teaching assistants 1 person, 3 postdoctoral students, 5 doctoral students 1 person, and enterprises jointly train postdoctoral students 1 person. There are three laboratories for graphene, new energy materials and polymer chemistry, and the "Zhejiang University-Carbon Valley on the West" 1 Joint Research Center.
The team has been committed to the large-scale preparation and macro-assembly of single-layer graphene oxide for a long time, and discovered the liquid crystal properties of graphene oxide, invented four pure graphene macro-materials (F4 for short): graphene fiber, graphene nonwoven fabric, graphene continuous assembly film and the lightest material graphene aerogel, and developed six core technologies, including low-cost and high-quality single-layer graphene oxide, multifunctional graphene composite fiber, graphene high-efficiency electrothermal cloth, graphene supercapacitor, graphene aluminum ion battery and graphene nanofiltration membrane. Some of these achievements have broad prospects for industrialization.
Gao Chao, born in June, 1973, Tujia, Qiushi distinguished professor, Zhejiang University, doctoral supervisor, director of the Institute of Polymer Science.
1995 received a bachelor's degree from Hunan university, 1998 received a master's degree, and 200 1 received a doctorate from Shanghai jiaotong university. After graduating from Ph.D., he stayed in Shanghai Jiaotong University to teach. From 2003 to 2006, he was a visiting scholar and postdoctoral researcher at the University of Sussex in the UK and the University of reuter in Germany. In 2008, he was introduced to Zhejiang University and awarded as a professor and doctoral supervisor.
* * * 1 Editor-in-Chief Wiley published the English monograph Hyperbranched Polymers: Synthesis, Properties and Applications, which wrote 6 chapters for the English monograph and won 23 invention patents in China.
As the regional editor-in-chief of the international journal Colloid and Polymer Science.
He has been selected or awarded the Young and Middle-aged Leading Talents Program of Science and Technology Ministry (20 14), National Outstanding Youth Fund (20 13), Zhejiang Qianjiang Talent Program (20 10), Shanghai Pujiang Talent Program (2007), Ministry of Education Outstanding Talents Program (2007) and other talent programs in Shanghai.
Main achievements: (1) The chiral liquid crystal phase of graphene oxide liquid crystal and two-dimensional colloidal particles was discovered, and the continuous graphene fiber was proposed and realized;
(2) realizing high-performance graphene fiber supercapacitor and graphene-based nanofiltration membrane;
(3) Ultralight elastic aerogels were prepared by template-free collaborative assembly strategy.
(4) Invented a green, ultra-fast and safe iron-based method, which can prepare a large number of single-layer graphene oxide, breaking through the traditional preparation method with high pollution, easy explosion and long time since 1958.
Single-layer graphene can be prepared by iron-based method within 1 hour. It is expected to realize large-scale industrial application.
Now, this heart-shaped graphene assembly film should be added to the results. This research achievement has been commented by Nature, Natural News, Scientific American and other highlights, saying that it has "realized a key step in the application of graphene in real devices" and "opened up a new way to prepare carbon fibers", and has been followed up by many research groups in the United States, France, Australia and China.
On April 20 17, the editorial department of New Materials, the world flagship journal of materials science, invited various research groups related to high-tech materials in Zhejiang University to write articles and show the research achievements of Zhejiang University in the field of material chemistry in the form of a celebration album, so as to present the 20th anniversary of Zhejiang University/KLOC-0.
Graphene fiber knot was selected in Nature 20 1 1 annual picture, which is the only scientific and technological achievement in China since 2005. Ultra-light aerogels were highly praised by Nature twice.
It was certified as the lightest solid material by Guinness World Records, won the "Golden Kangaroo" innovation award of the World Innovation Forum, and was selected as the top ten scientific and technological progress news in China in 20 13 by academicians of the two academies.
Paper crane folding adopts the latest high thermal conductivity ultra-flexible graphene film.
Peng Li, Ph.D., Department of Polymer Science and Engineering, won the "Qizhen Cup" award for the top ten academic achievements of Zhejiang University students in 20 16 for his scientific paper "Rapid Green Preparation of Graphene Oxide".
Recently, Zhejiang University Press Office, qianjiang evening news and other media reporters interviewed the team of Professor Gao Chao from the Department of Polymer Science of Zhejiang University. Facing the reporter, Professor Gao Chao said that electronic appliances will generate heat when working, and efficient thermal management is needed to ensure their normal operation. A new generation of equipment also needs flexibility. Therefore, it is very important to study materials with high thermal conductivity and high flexibility. However, the high thermal conductivity and high flexibility of the existing macro materials are a contradiction that it is difficult for a pair of fish and bear's paw to have both.
The appearance of graphene provides a theoretical possibility for solving this contradiction. It is a honeycomb planar monolayer two-dimensional macromolecule formed by the hybridization of carbon atoms sp2. The light, simple and strong bonding structure of atoms endows them with ultra-high thermal conductivity; At the same time, the thickness of the monoatomic layer makes it flexible. Unfortunately, the existing exfoliated graphene sheets are small and have many defects, and the macroscopic materials assembled from them have poor thermal conductivity and flexibility, which are not as good as the commercial polyimide graphitized film (GPI). For example, the radiator in our mobile phone is made of GPI.
Andre Geim, the Nobel Prize winner who discovered graphene, is an honorary professor of Zhejiang University. The discovery of graphene deserves a Nobel Prize. The new graphene assembly film can be applied to aerospace and smart phones in the future, with greater value.
In Professor Gao Chao's office, the reporter saw a piece of graphene assembled membrane with a length of 20 cm, which looked like a large piece of instant seaweed. According to Gao Chao, this 10 micron thick "seaweed" is composed of several thousand layers of graphene. The experimental results show that the graphene film can withstand more than 654.38+ million bends without affecting its thermal and electrical conductivity, and it still does not break after repeated folding for 6000 times. The GPI with the best performance before can only be folded repeatedly for up to 3 times. At the same time, the thermal conductivity of this graphene film is as high as 2053W/mK (watt/meter-degree), which is close to 40% of the thermal conductivity of the ideal single-layer graphene, creating a new record for the thermal conductivity of macroscopic materials.
Figure 1. A) the back of a commercially available smartphone; B) The mobile phone is in standby state; C) using polyimide graphitized film (GPI) as the heat dissipation film of mobile phone; D) The novel graphene film is used as the heat dissipation film of the same mobile phone; E, f) Compared with the horizontal and vertical temperature lines of the mobile phone in three states (b), (c) and (d), graphene film has better heat dissipation and cooling effect.
Soft and high thermal conductivity gives us unlimited imagination, such as foldable mobile phones, laptops, and even satellites and spaceships. The research group used this graphene film to replace the commercial GPI film and applied it to the heat dissipation film of mobile phones. It is found that the temperature at the CPU of the mobile phone can be controlled below 33℃, which is 6℃ lower than that of the GPI film on the market. If this film is applied to artificial satellites, it can solve the problem of large temperature difference of satellite backlight.
Peng Li said that the heat dissipation of electronic components is a very important issue in equipment development. They are "afraid of heat" because these power devices have a stable working temperature range. With the increase of temperature, the stability of the device will decrease, the noise will increase and the life will decrease. Generally speaking, if the temperature rises by 8- 10 degrees, the lifetime of the device will be reduced by half. According to statistics, temperature accounts for more than 50% of the failure causes of electronic products.
How did scientists change graphene film from "fragile" to "soft" with good thermal conductivity? Gao Chao said that the team put forward the design idea of "large-scale micro-folds", and introduced many tiny folds in the process of preparing graphene films, making graphene films a "flexible" material. Just like a girl's pleated skirt, the skirt can be greatly unfolded. How to make such a tiny wrinkle? The superb team came up with a novel method: heating the graphene film at high temperature, decomposing and releasing oxygen-containing functional groups in the film at high temperature, and forming microspheres inside the graphene film; Then it is pressed into a film by a mechanical roller, and the gas in the micro balloon is exhausted to form micro-folds. "It's that simple," Gao Chao said.
Figure 2. The introduction process of graphene micro-folds: micro-balloons are formed by high-temperature heating and reduction, and micro-folds are formed by mechanical rolling.
Paper screenshots, folding greatly enhanced the ability of the film to withstand bending during the folding process.
"Advanced Science News" commented that this achievement enables many large-area and multifunctional two-dimensional materials to be applied to flexible devices in the real world, from aerospace to smart phones.
Advanced Science News believes that this design concept and experimental strategy can be extended to other two-dimensional nanomaterials.