Featured Research

from universities, journals, and other organizations

Physicists solve 20-year-old debate surrounding how glassy surfaces flow like a liquid

Date:
February 28, 2014
Source:
University of Waterloo
Summary:
Physicists have succeeded in measuring how the surfaces of glassy materials flow like a liquid, even when they should be solid. A series of simple and elegant experiments were the solution to a problem that has been plaguing condensed matter physicists for the past 20 years.

Graph showing how the top surface of a glassy polymer moves like a liquid.
Credit: Image courtesy of University of Waterloo

University of Waterloo physicists have succeeded in measuring how the surfaces of glassy materials flow like a liquid, even when they should be solid.

A series of simple and elegant experiments were the solution to a problem that has been plaguing condensed matter physicists for the past 20 years.

Understanding the mobility of glassy surfaces has implications for the design and manufacture of thin-film coatings and also sets practical limits on how small we can make nanoscale devices and circuitry.

The work is the culmination of a project carried out by a research team led by Professor James Forrest and doctoral student YuChai from the University of Waterloo as well as researchers from ÉcoleSuperieure de Physique et de ChimieIndustrielles in France and McMaster University.

Their groundbreaking work was published in the scientific journal, Science, this week.

"Glasses are fascinating materials. At low temperatures they're solid, and at higher temperatures they're liquid. At intermediate temperatures, it's hard to consider them as only one or the other," said Professor Forrest. "Surfaces of glassy polymers shouldn't flow below the glass transition temperature, but they do. The question is why."

Glass is much more than the material in bottles and windows. In fact, any solid without an ordered, crystalline structure is considered a glassy material, so metals, small molecules, and polymers can all be made into glassy materials.

Polymers, the building block of all plastics, are almost always glassy rather than crystalline. These materials undergo a transition between a brittle solid and a molten liquid in a narrow temperature range, which encompasses the so-called glass transition temperature.

In a series of experiments, Forrest and colleagues started with very thin slices of polystyrene stacked to create tiny staircase-like steps about 100-nanometres high -- less than 0.001 per cent the thickness of a human hair. They then measured these steps as they became shorter, wider and less defined over time.

The simple 2-dimensional profile of this surface step allowed the physicists to numerically model the changes to the surface's geometry above and below the glass transition temperature.

Results show that above the transition temperature, polystyrene flows entirely like a liquid; but below this temperature the polymer becomes a solid with a thin liquid-like layer at the surface.

Being able to calculate how these nanostructures may evolve over time and under what conditions will bring engineers a step further towards making nanotechnology an everyday reality.

Professor Forrest and doctoral student Yu Chai are from the Department of Physics and Astronomy in the Faculty of Science. Forrest is also a University Research Chair, a member of the Waterloo Institute for Nanotechnology and an associate faculty member at the Perimeter Institute.

The project team also includes Kari Dalnoki-Veress and J.D. McGraw from McMaster University and Thomas Salez, Michael Benzaquen and Elie Raphael of the École Superieure de Physique et de Chimie Industrielles in Paris.


Story Source:

The above story is based on materials provided by University of Waterloo. Note: Materials may be edited for content and length.


Journal Reference:

  1. Y. Chai, T. Salez, J. D. McGraw, M. Benzaquen, K. Dalnoki-Veress, E. Raphael, J. A. Forrest. A Direct Quantitative Measure of Surface Mobility in a Glassy Polymer. Science, 2014; 343 (6174): 994 DOI: 10.1126/science.1244845

Cite This Page:

University of Waterloo. "Physicists solve 20-year-old debate surrounding how glassy surfaces flow like a liquid." ScienceDaily. ScienceDaily, 28 February 2014. <www.sciencedaily.com/releases/2014/02/140228121353.htm>.
University of Waterloo. (2014, February 28). Physicists solve 20-year-old debate surrounding how glassy surfaces flow like a liquid. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2014/02/140228121353.htm
University of Waterloo. "Physicists solve 20-year-old debate surrounding how glassy surfaces flow like a liquid." ScienceDaily. www.sciencedaily.com/releases/2014/02/140228121353.htm (accessed July 31, 2014).

Share This




More Matter & Energy News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) — British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) — A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) — Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com
U.K. To Allow Driverless Cars On Public Roads

U.K. To Allow Driverless Cars On Public Roads

Newsy (July 30, 2014) — Driverless cars could soon become a staple on U.K. city streets, as they're set to be introduced to a few cities in 2015. Video provided by Newsy
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