Waterloo physicists solve 20-year-old debate surrounding glassy surfaces

Date: 6 March 2014

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 Yu Chai from the University of Waterloo as well as researchers from École Superieure de Physique et de Chimie Industrielles in France and McMaster University.Their groundbreaking work was published in the prestigious 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.

Graph showing how the top surface of a glassy polymer moves like a liquid  

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.



About the University of Waterloo


In just half a century, the University of Waterloo, located at the heart of Canada's technology hub, has become one of Canada's leading comprehensive universities with 35,000 full- and part-time students in undergraduate and graduate programs. Waterloo, as home to the world's largest post-secondary co-operative education program, embraces its connections to the world and encourages enterprising partnerships in learning, research and discovery. In the next decade, the university is committed to building a better future for Canada and the world by championing innovation and collaboration to create solutions relevant to the needs of today and tomorrow. For more information about Waterloo, please visit www.uwaterloo.ca.

600450 Waterloo physicists solve 20-year-old debate surrounding glassy surfaces glassonweb.com

See more news about:

Others also read

Coinciding with the fulfillment of the ARTESUN project´s first year (November), the third Project Meeting took place at Corning headquarters in Avon, France    Funded by the European Comission through its Seventh Framework Programme, ARTESUN Project aims to develop organic photovoltaic solar cells (OPV) through the implementation of three full-scale prototypes.
"Opportunity in the Indian Glass Market - 2014 : Market size, Market share, Market landscape, Market trend analysis, Growth drivers, Future opportunity, Future forecast" provides an insight into the Indian Glass current market scenario, structure and practices.
Dubai Investments (DI) CEO Khalid Bin Kalban has revealed that the Company seeks to examine several expansion opportunities in 2015.
This report was created for strategic planners, international executives and import/export managers who are concerned with the market for nonwired glass sheets of float glass and surface ground or polished glass.
New Business to Support Company's Growing Presence in East and Central African Markets - H.B. Fuller Company (NYSE: FUL) announced today that it has signed an agreement to purchase Continental Products Limited, a provider of industrial adhesives in East and Central Africa.
Brazil’s Foreign Trade Chamber (Camex), the federal government’s policy-making body for the sector, has decided to levy definitive antidumping duties on float glass imports from six countries, including Arab countries Saudi Arabia, United Arab Emirates and Egypt.

Add new comment