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Past Winner
2004 E.W.R. Steacie Memorial Fellowship

Mosto Bousmina

Polymer Engineering

Université Laval

Mosto Bousmina
Mosto Bousmina

As a young boy growing up in Strasbourg, France, the son of a working-class Moroccan family, Mosto Bousmina was enraptured by magic. He knew that he was watching illusion, but he revelled in the arrival of the seemingly impossible. Soon he began creating his own tricks, experimenting with the special properties of materials as he found them: magnets, elastics and various solids and liquids.

Today the Université Laval polymer engineering professor is still mixing materials, devoted to understanding their basic properties and their potential – and still creating gasps of surprise. The latest high-tech trick he's working on? Turning a lump of clay into a transparent, ultra-light, bullet-proof material.

One of six recipients of a 2004 NSERC E.W.R. Steacie Memorial Fellowship, Dr. Bousmina is a specialist in discovering the way in which plastics, and their additives, flow and mix. His laboratory is a world leader in this field, technically called the rheology of multiphase polymeric systems.

"If you want to change a material's qualities, for example, its strength or conductivity, you have to do it in the molten state. You need to understand how the material flows and how changing this will change the material's final properties," says Dr. Bousmina, the Canada Research Chair in Polymer Physics and Nanomaterials.

The science of polymer flow affects our lives from the feel of the toothbrush we use in the morning to the light switch we push when we go to bed. The names of these ubiquitous polymers are the vocabulary of our increasingly plastic world: polyurethane, PVC, polystyrene, ABS and polycarbonate.

As an engineer, just as he is as a magician, Dr. Bousmina is never content to see that something simply works. His passion has always been to grasp the fundamental properties that lie behind a process, and thus be able to predictively extend these properties to other situations by modeling the process using advanced mathematics, his favourite branch of science.

His first major scientific coup was extending Albert Einstein's 1911 equation describing how a liquid's viscosity changes when hard spheres are added. Dr. Bousmina modified the equation and extended it to viscoelastic media (i.e., liquids that flow like water and relax like springs) containing deformable and viscoelastic spheres; for example, how the presence of red blood cells affects blood's flow. This equation is now used worldwide in industrial and research applications to predictively determine a material's end properties.

At the core of this extension of Einstein's viscosity equation was a fundamental mathematical understanding of the marvellous effects that changes in curvature can have on a material. Again using this insight, Dr. Bousmina developed, in collaboration with his colleague Dr. Kaliaguine, a method to mathematically determine the porosity of soft materials by filling them with water. The curvature of the pores can dramatically change water's freezing point to as low as -40ºC.

"From the change in the freezing point, we can determine the pore size and the pore size distribution in both soft and hard materials," says Dr. Bousmina.

The technique is now recognized by the U.S. Food and Drug Administration as the only one suitable for the assessment of porosity in biological, hydrogel and soft materials.

As an NSERC Steacie Fellow, Dr. Bousmina is bringing an ancient material into the age of nanotechnology.

"We're imitating nature in our work with clay and other nanomaterials," says Dr. Bousmina, always one to be watching others' techniques.

Spiders' silk and bone are enormously strong because of their billionth-of-a-metre, or nanometre, level properties. A bone's strength comes from nanometre long pieces of calcium phosphate integrated into a collagen and cellular matrix.

At the level of the potter's wheel, clay is an opaque, dense solid. But, its essential composition is similar to phyllo pastry, with nanometre thick layers. If you can separate these layers and disperse them into another substance, the addition of just two to six percent of clay nanoparticles could create products stronger, and much lighter, than some present composites that are 50 percent glass fibre.

"Nanomaterials offer lots of opportunities in creating materials with unique mechanical, electrical and barrier properties. But we're just at the beginning of our understanding. We don't know how to disperse this material at the nanoscale level. There are already some commercial nanomaterial products but these are made by trial and error. We don't understand the basic science behind this," says Dr. Bousmina.

In his effort to see behind nature's nanomaterial slight of hand, Dr. Bousmina's 21-person lab will be focusing on how to effectively delaminate the nanoscale layers of clay, including using ultrasound to measure the exact energy required to separate two layers.