Stimuli Responsive Polymer Colloids
NSERC – Discovery Grant Program – Individual

The next generation of advanced materials will be capable of responding to variation in their environment by undergoing changes in their chemical or physical properties. The stimulus to which the materials react is known as a “trigger”, and such materials are commonly known as “stimuli-responsive” materials. The proposed research program will examine a new class of polymer nanoparticles. These are very small particles (~100 nm in diameter, or 1000x smaller than the thickness of a human hair) that find application in a wide range of products, many of significant economic importance to Canada, including for example coatings, sealants, adhesives, personal/health care products and cosmetics. What we will do is develop new methods for making these nanoparticles stimuli responsive, so that the particles will undergo a desirable or beneficial change in their properties upon exposure to a trigger that will make them more useful or valuable for a given application. Well known examples of stimuli-responsive materials include windows that darken upon exposure to bright light. Our research group recently introduced polymer nanoparticles that can undergo a dramatic change in properties upon exposure to simple, benign triggers; carbon dioxide or air. In contrast, other existing stimuli-responsive polymer particles require toxic chemicals such as strong acids or bases to switch. We need only bubble carbon dioxide or air into a water-based suspension of our particles to switch their surface properties so that the particles exist either as a uniform dispersion (under carbon dioxide) or as an aggregated powder (under air). This is achieved because the particle surface electrical charge can be “switched”. We will develop processes for making three different types of carbon dioxide responsive nanoparticles. One type will use established chemistry commonly used in existing products, the second type will use a novel chemistry suitable for advanced, high valued added applications, while the third type will employ a novel, switchable renewable nanomaterial derived from cellulose (a critical resource for Canada), known as CNC (crystalline nanocellulose). Students conducting the research will develop a broad understanding of both stimuli-responsive materials and polymer nanoparticles, preparing them for making important contributions to Canada’s future economic development in key industrial sectors.

Stimuli-responsive materials are currently the subject of intense research interest because of their potential for application in both commodity and high value added materials. They have significant potential for advancing several industries in which they are already widely used, as well as being a cornerstone for new products and applications. The use of benign triggers (carbon dioxide, air) to enact the switching behaviour is particularly attractive and unique.