Featured Research

from universities, journals, and other organizations

From Bubbles To Capsules

Date:
September 7, 2006
Source:
John Wiley & Sons, Inc.
Summary:
Researchers from Japan have developed a clever new technique for the production of silicon dioxide nanocapsules: they start with tiny bubbles of carbon dioxide in a silicon copolymer.

Nanocapsules are vessels with diameters in the nanometer range and very thin shells. They can store a tiny volume of liquid and can protect their cargo while transporting it through a foreign medium — such as a human blood vessel — without any loss. Further applications for nanocapsules include the encapsulation of scents, printer ink, and adhesives.

Related Articles


Once at their destinations, the payloads are released by pressure or friction. Japanese researchers have now developed a clever new technique for the production of silicon dioxide nanocapsules: they start with tiny bubbles of carbon dioxide in a silicon copolymer.

Lei Li and Hideaki Yokoyama coated silicon wafers, which act as a support, with thin films of a special plastic that consists of molecules with segments of different types of polymers, so-called block copolymers, in this case made of polystyrene and silicone. The researchers made their copolymer films such that nanoscopic “droplets” of silicone “float” in a matrix of polystyrene. Supercritical carbon dioxide (CO2) is then forced into this film under high pressure at 60 C.

(In a supercritical fluid, it is impossible to distinguish between the liquid and gas phases.)

The CO2 lodges within the droplets of silicone in the block copolymer and forms bubbles. It cannot force its way into the polystyrene matrix, however. In the next step, the scientists cool the film down to 0 C in order to freeze the polystyrene matrix and then slowly reduce the pressure back to atmospheric levels. The CO2 returns to the gas phase, expands, and escapes from the bubbles without collapsing them.

Finally, the researchers expose the polymer film to ozone and UV light. Under these conditions, the polystyrene matrix is completely destroyed; the silicone surrounding the bubbles is oxidized to silicon dioxide (SiO2). This results in a thin film of tightly packed, tiny cavities with a thin shell of silicon dioxide. These nanocapsules have diameters of less than 40 nanometers and walls that are about 2 nanometers wide.

The particular advantage of this method is that the resulting nanocapsules are organized into a two-dimensional structure that can be controlled by varying the segments of the block copolymer.


Story Source:

The above story is based on materials provided by John Wiley & Sons, Inc.. Note: Materials may be edited for content and length.


Cite This Page:

John Wiley & Sons, Inc.. "From Bubbles To Capsules." ScienceDaily. ScienceDaily, 7 September 2006. <www.sciencedaily.com/releases/2006/09/060907102359.htm>.
John Wiley & Sons, Inc.. (2006, September 7). From Bubbles To Capsules. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2006/09/060907102359.htm
John Wiley & Sons, Inc.. "From Bubbles To Capsules." ScienceDaily. www.sciencedaily.com/releases/2006/09/060907102359.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. 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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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