Featured Research

from universities, journals, and other organizations

Self-assembled Nanostructures Function Better Than Bone As Porosity Increases

Date:
July 26, 2007
Source:
Sandia National Laboratories
Summary:
Naturally occurring structures like birds' bones or tree trunks are thought to have evolved over eons to reach the best possible balance between stiffness and density. Researchers now show that nanoscale materials self-assembled in artificially determined patterns can improve upon nature's designs. The silica nanostructures -- basically a synthetic analogue of bone-like cellular structures, replicated at the nanoscale using silica compounds -- thus may improve performance where increased pore volume is important.

Naturally occurring structures like birds’ bones or tree trunks are thought to have evolved over eons to reach the best possible balance between stiffness and density.

But in a June paper in Nature Materials, researchers at Sandia National Laboratories and the University of New Mexico (UNM), in conjunction with researchers at Case Western Reserve and Princeton Universities, show that nanoscale materials self-assembled in artificially determined patterns can improve upon nature’s designs.

“Using self-assembly we can construct silica materials at a finer scale than those found in nature,” says principal investigator Jeff Brinker. “Because, at very small dimensions, the structure and mechanical properties of the materials change, facile fabrication of stiff, porous materials needed for microelectronics and membrane applications may be possible.”

Nuclear magnetic resonance and Raman spectroscopic studies performed by Sandia researchers Roger Assink (ret.) and Dave Tallant, along with molecular modeling studies performed by Dan Lacks at Case Western Reserve University, showed that, as the ordered porous films became more porous, the silica pore walls thinned below 2 nm, re-arranging the silica framework to become denser and stiffer.

Whereas the stiffness of evolved optimized bone declines proportional to the square of its density, mechanical studies performed by Sandia researcher Thomas Buchheit working with UNM student Christopher Hartshorn showed that the stiffness/modulus of self-assembled materials was much less sensitive to increasing porosity: For a material synthesized with a cubic arrangement of pores, the modulus declined only as the square root of its density.

The silica nanostructures — basically a synthetic analogue of bone-like cellular structures, replicated at the nanoscale using silica compounds — thus may improve performance where increased pore volume is important. These include modern thin-film applications such as membrane barriers, molecular recognition sensors, and low-dielectric-constant insulators needed for future generation of microelectronic devices.

“Bone, closely examined, is a structured cellular material,” says Brinker, a Sandia Fellow and chemical engineering professor at UNM. “Because, using self-assembly, we had demonstrated the fabrication of a variety of ordered cellular materials at the nanoscale with worm-like (curving cylinders), hexagonal (soda straw packing) and cubic sphere arrangements of pores, we wondered whether the modulus-density scaling relationships of these nanoscale materials would be similar to the optimized evolved materials [like bone]. We found that both material structure and pore sizes matter. At all densities we observed that the cubic arrangement was stiffer than the hexagonal arrangement, which was stiffer than the worm-like. For each of these structures, increasing porosity caused a reduction in modulus, but the reduction was less than for theoretically optimized or naturally evolved materials due to the attendant stiffening of the thinning nanoscale silica walls resulting from the formation of small stiff silica rings.

“This change in ring structure only happens at the nanoscale,” says Brinker.

Sandia researcher Hongyou Fan created cubic, cylindrical, and worm-like (or disordered) pores to evaluate differences in stiffness resulting from these differently shaped internal spaces.

Other paper authors include Dave Kissel of UNM, Regina Simpson at Sandia, and Salvatore Torquato of Princeton. Sandia is a National Nuclear Security Administration laboratory. Funding for the research was provided by DOE’s Office of Science and Sandia’s Laboratory Directed Research and Development Program.


Story Source:

The above story is based on materials provided by Sandia National Laboratories. Note: Materials may be edited for content and length.


Cite This Page:

Sandia National Laboratories. "Self-assembled Nanostructures Function Better Than Bone As Porosity Increases." ScienceDaily. ScienceDaily, 26 July 2007. <www.sciencedaily.com/releases/2007/07/070721191346.htm>.
Sandia National Laboratories. (2007, July 26). Self-assembled Nanostructures Function Better Than Bone As Porosity Increases. ScienceDaily. Retrieved August 28, 2014 from www.sciencedaily.com/releases/2007/07/070721191346.htm
Sandia National Laboratories. "Self-assembled Nanostructures Function Better Than Bone As Porosity Increases." ScienceDaily. www.sciencedaily.com/releases/2007/07/070721191346.htm (accessed August 28, 2014).

Share This




More Matter & Energy News

Thursday, August 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Chinese Researchers Might Be Creating Supersonic Submarine

Chinese Researchers Might Be Creating Supersonic Submarine

Newsy (Aug. 26, 2014) Chinese researchers have expanded on Cold War-era tech and are closer to building a submarine that could reach the speed of sound. Video provided by Newsy
Powered by NewsLook.com
Breakingviews: India Coal Strained by Supreme Court Ruling

Breakingviews: India Coal Strained by Supreme Court Ruling

Reuters - Business Video Online (Aug. 26, 2014) An acute coal shortage is likely to be aggravated as India's supreme court declared government coal allocations illegal, says Breakingviews' Peter Thal Larsen. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins