Nature China highlights the best research coming out of Mainland China and Hong Kong, providing scientists from around the world with a convenient portal into publications drawn from across all scientific disciplines. Each week, our editors select the best published research and provide a summary of the results. By organizing this research into a comprehensive, regularly updated, one-stop web portal, we hope to help you quickly reach the resources you need to study, and to keep you up-to-date with the most significant research coming out of Mainland China and Hong Kong.
http://www.nature.com/nchina/index.html
------------------------------------------------------------------------------------------
Porous materials: Forced to order
Vicki Cleave
Abstract
High-temperature drying of composite solutions leads to ordered pores in polymer films
Original article citation
You, B.
et al. A facile method for fabrication of ordered porous polymer films. Macromolecules doi: 10.1021/ma801417c (2008).
Introduction
© (2008) ACS
Porous films — especially those with three-dimensionally ordered pores — are useful for many applications, such as photonics, biosensing and catalysis. However, the fabrication of ordered pores in films often requires complex procedures, including the making, use and removal of a template, as well as precise controls that are unsuitable for mass production. To address these problems, Limin Wu and co-workers at Fudan University in Shanghai
1 have introduced a 'forced drying' method that has just one step, can be used with any substrate, and enables control of the pore size.
The researchers stirred latex polymer nanoparticles and silica nanoparticles, which were hundreds and tens of nanometres in diameter, respectively, into water. They then cast the polymer solution — by spin-coating, brush-coating or pouring — onto a variety of substrates, such as glass, silicon wafer and plastic. After drying the sample at high temperatures (above 120 °C) for two hours or more, a periodic array of pores was formed in the film (pictured).
Changing the polymer nanoparticle size controls the pore sizes and distribution. The exact formation mechanism has yet to be explained, but Wu and co-workers showed that silica particles are vital — without them, no porous structure would form.
The authors of this work are from:
Department of Materials Science and Advanced Materials Laboratory, Fudan University, Shanghai, China.
Reference
- You, B. et al. A facile method for fabrication of ordered porous polymer films. Macromolecules doi: 10.1021/ma801417c (2008). | Article |
Hybrid materials: Well spread
Vicki Cleave
Abstract
A chemical approach ensures nanoparticles are well dispersed in hybrid materials
Original article citation
Liu, X.
et al. Organic–inorganic nanohybrids via directly grafting gold nanoparticles onto conjugated copolymers through the Diels–Alder reaction. Langmuir doi: 10.1021/la8020639 (2008).
Introduction
© (2008) ACS
Hybrid materials are a topic of intense interest at present because they provide the potential to combine the best properties of different components into one material. Unfortunately, favourable properties are often lost as a result of the poor dispersion of components within the material. Yuliang Li at the Chinese Academy of Sciences in Beijing and co-workers
1 have developed a chemical approach that avoids this problem.
The researchers produced a composite of two electronically active components — namely, conjugated polymers and gold nanoparticles. They functionalized the gold nanoparticles with maleimide groups, and used a polymer with furan pendant groups branching off from its conjugated backbone (pictured), so that they could bring them together using the Diels–Alder reaction.
The Diels–Alder reaction is one of the most important ways in which chemists make new carbon–carbon bonds, and here it proceeds under very mild conditions: at room temperature, in chloroform and away from light. As the polymer and nanoparticles come together, their electronic spectra are influenced by each other's presence, so the reaction can be monitored simply from the change in the mix's ultraviolet-to-visible spectrum.
The components were well dispersed throughout the final hybrid, giving it the cumulative properties of their electronic and optical signatures and pronounced nonlinear optical properties that promise novel device applications.
The authors of this work are from:
Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Organic Solids, Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China; Graduate University of Chinese Academy of Sciences, Beijing, China; Suzhou University, Suzhou, China; Department of Physics, Harbin Institute of Technology, Harbin, China.
Reference
- Liu, X. et al. Organic–inorganic nanohybrids via directly grafting gold nanoparticles onto conjugated copolymers through the Diels–Alder reaction. Langmuir doi: 10.1021/la8020639 (2008). | Article |
Fullerenes: Symmetry breakers
Felix Cheung
Abstract
Researchers in Xiamen are close to making symmetry-breaking buckminsterfullerenes
Original article citation
Tan, Y. Z.
et al. Two Ih-symmetry-breaking C60 isomers stabilized by chlorination. Nature Mater. doi: 10.1038/nmat2275 (2008).
Full text article available for download free
Introduction
© (2008) Nature Materials
Buckminsterfullerene (C60) was discovered more than two decades ago. However, icosahedrally symmetric C60 (
Ih-C60), which resembles a soccer ball, remains the only C60 species that can be made in an experiment. Structural variations of C60 — especially those without icosahedral symmetry — might be possible, but nobody has figured out how to make them yet. Suyuan Xie and co-workers at Xiamen University
1 have now produced two chlorinated symmetry-breaking C60 species — just one step away from an actual symmetry-breaking C60 structure.
The carbon atoms of
Ih-C60 are arranged in hexagons and pentagons, in which no two pentagons share an edge. Fusing pentagons together would make the C60 structure unstable, so Xie and co-workers overcame this problem by adding chlorine atoms at the edges of the fused pentagons. They managed to produce two symmetry-breaking species, C60Cl8 and C60Cl12 (pictured), both of which contained fused pentagons in their structure.
When the researchers optimized the reaction conditions, they could improve the yield of the C60Cl8 to 3.5% the weight of the crude product, which is comparable to the 4.2% yield of
Ih-C60. The yield of C60Cl12 is much lower, but still enough for detailed characterization and property investigations in future studies.
The authors of this work are from:
State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China.
Reference
- Tan, Y. Z. et al. Two Ih-symmetry-breaking C60 isomers stabilized by chlorination. Nature Mater. doi: 10.1038/nmat2275 (2008). | Article |
[
本帖最后由 sally208 于 2008-9-25 11:35 编辑 ]
- 