Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nanoscale Cubes and Spheres

08.01.2007
Uniform porous silicon oxide nano-objects formed by controlled disassembly of a lattice structure

Porous nano-objects with defined sizes and structures are particularly interesting, for example, as capsules for enzymes, a means of transport for pharmaceutical agents, or building blocks for larger nanostructures. The production of such tiny, three-dimensional objects in a targeted and controlled manner—and as simply and efficiently as possible—remains a challenge for scientists.

At the University of Minnesota, a team led by Andreas Stein has now developed an interesting new process for the production of nanoscopic cubes and spheres of silicon dioxide. The researchers reported their trick in Angewandte Chemie: Instead of building their particles from smaller units, they used the controlled disassembly of larger, lattice-like structures.

Most conventional methods for the production of porous silicon dioxide nanoparticles suffer from the fact that the growing particles tend to aggregate (clump together), making it difficult to achieve a uniform size. The shape of the particles can hardly be influenced at all. Stein and his team chose a backward approach, first building up a lattice structure of silicon dioxide and then disassembling it to get the shape they wanted. The “moulds” used for the lattice were tiny spheres of a plastic called polymethylmethacrylate (PMMA), which assemble themselves through “closest packing of spheres” into a colloidal crystal. Between the spheres in this structure, there are little, nearly tetrahedral and nearly octahedral spaces. The researchers filled these cavities with a solution containing an organosilicon compound, oxalic acid, and a surfactant.

... more about:
»Silicon »controlled »dioxide »lattice

This mixture hardens into a solid gel. The plastic spheres and surfactant are then burned off by heating. The surfactant leaves behind tiny pores, and the gelled organosilicon compound slowly converts to a solid silicon oxide. What remains initially is a silicate lattice that is the negative of the packed spheres: tiny tetrahedra and octahedra attached to each other by delicate bridges. As the conversion to silicon dioxide continues, the structure shrinks until it breaks at the weakest points—the bridges. The fragments formed by this process are shaped like octahedra or smaller tetrahedra. These continue to contract until the octahedra become nearly cubic and the tetrahedra become nearly spherical, making highly uniform structures with worm-like pores.

By varying the colloidal crystals used as the mould, the size and shape of the resulting particles can be controlled. Through vapor deposition or polymer grafting, other compounds can be added to the structure. Subsequent etching away of the silicon oxide allows this new technique to be used as a starting point for nanostructures made of other materials.

Andreas Stein | EurekAlert!
Further information:
http://www.chem.umn.edu

Further reports about: Silicon controlled dioxide lattice

More articles from Life Sciences:

nachricht Navigational view of the brain thanks to powerful X-rays
18.10.2017 | Georgia Institute of Technology

nachricht Separating methane and CO2 will become more efficient
18.10.2017 | KU Leuven

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>