Replacing traditional surfactants in the preparation of polymer nanoparticles

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Several important, large volume commercial products including automotive tires, paints, coatings, sealants and adhesives are made in manufacturing processes that require the use of large amounts of surfactants, also commonly known as detergents, emulsifiers or soaps. Their role is to stabilize the small polymer (plastic, rubber) particles which are dispersed in water by preventing them from coagulating. This is a global market worth over $50 billion (CAD) annually that uses approximately 400,000 tonnes of surfactant per year. The surfactants are essential to making these products, but they cannot be removed or recovered. Consequently the surfactants end up in the environment where they pose serious toxicity and environmental concerns, either by leaching out of the product during its service life, or when the product ends up in a landfill. Furthermore, they are petroleum-based and therefore non-renewable. Recognizing these problems, industry is actively seeking alternatives to conventional surfactants, however despite their intensive research efforts no promising candidates have emerged. An ideal replacement would be non-toxic and renewably sourced. This research proposal will explore a new type of stabilizer for polymer particles, capable of replacing existing surfactants but having a very different design, eliminating the environmental and toxicity concerns, and additionally being renewably sourced, or bio-based. Almost a century ago it was first recognized that nano-size solid particles of silica (much like sand, only much smaller) were able to stabilize oil-in-water emulsions. However this discovery remained little more than a curiosity until recently when increasing interest has been shown for these "Pickering emulsifiers", primarily for use in the food industry as well as higher end cosmetics and personal care products. These applications involve stabilizing relatively large oil droplets or waxy particles. Given the recent interest in Pickering emulsifiers, an intriguing question is whether it is possible, and/or practical, to use a similar approach to replace conventional surfactants in the polymer-based processes described above. Recent progress at Queen's and elsewhere has offered encouragement that such an undertaking may be possible. The proposed research program will therefore endeavor to develop a new class of bio-based alternatives to conventional surfactants based on nanoparticles made from cellulose, starch, chitin or chitosan. There are very few previous studies using bio-based nanoparticles to make polymer particles, presenting an opportunity to make significant scientific and commercial impacts. The benefits would be global. Benefits to Canada, in addition to health and environmental benefits due to reduced use of surfactants, would include economic benefits from being global leaders in bio-based Pickering emulsifiers including advanced training of several highly qualified personnel.