Versatile modification of surfaces using scalable gas-phase chemical reactions

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The size- and surface-driven properties of nanoparticles have attracted a great deal of research interest in the past decade. Indeed, nanoparticles are sufficiently small that they may be incorporated into other media to bring about new properties (enhanced strength, better heat transfer and electrical conductivity, optical absorbance, etc.) without significantly affecting the existing properties of the host media (weight or viscosity increase, flexibility, etc.) - these are called nanocomposites. Moreover, because of their small size, nanoparticles are also being studied in the field of biomedicine: they are small enough to cross certain cellular membranes and can thus act as drug carriers. However, there is one common step required to use nanoparticles in any of these applications: their surface must be pre-conditioned. Indeed, their high surface-to-volume ratio makes particle agglomeration a significant nuisance - untreated nanoparticles tend to agglomerate and form heavier structures that do not possess the desired "nano" properties. Beyond preventing agglomeration, the treatment step can be used to graft additional functionalities to the nanoparticle's surface, thus paving the way for more applications. While previous studies have successfully pre-conditioned nanoparticles using surfactants or liquid-based functionalization methods, these are now facing severe limitations. Surfactants desorb under the small heat loads commonly encountered in nanocomposite processing. While functionalization fares better in this area, the liquid-based approaches face their own share of issues: solvent compatibility, complex reactions, toxicity and difficulty in separating the functionalized particles from leftover reagents and/or by-products (issues that are compounded when attempting to form multifunctional surfaces). As such, the present research program will focus on more versatile gas-phase nanoparticle functionalization methods that are not subject to these limitations. Specifically, photo-initiated CVD will be the preferred functionalization tool, as it shows promise in tailoring particle surfaces. This work is expected to extend our capabilities to functionalize and tailor nanoparticles and will have a strong impact on the Canadian advanced materials sector.