Versatile modification of surfaces using scalable gas-phase chemical reactions

在过去的十年里，纳米颗粒的尺寸和表面驱动特性引起了人们极大的研究兴趣。事实上，纳米颗粒足够小，它们可以加入到其他介质中来带来新的性能(增强的强度、更好的导热和导电性、光吸收等)。在不显著影响宿主介质的现有性能(增加重量或粘度、柔韧性等)的情况下，这些被称为纳米复合材料。此外，由于纳米粒子的尺寸很小，因此在生物医学领域也在进行研究：它们足够小，可以穿过某些细胞膜，因此可以作为药物载体。然而，在任何这些应用中使用纳米颗粒都需要一个共同的步骤：它们的表面必须经过预处理。事实上，它们的高比表面积比使得颗粒团聚成为一种重大的滋扰--未经处理的纳米颗粒往往会团聚并形成更重的结构，而不具备所需的“纳米”特性。除了防止团聚，处理步骤还可以用来将额外的功能嫁接到纳米颗粒的表面，从而为更多的应用铺平道路。虽然以前的研究已经成功地使用表面活性剂或基于液体的官能化方法对纳米颗粒进行了预处理，但这些方法现在面临着严重的限制。表面活性剂在纳米复合材料加工中常见的小热负荷下解吸。虽然功能化在这一领域表现得更好，但基于液体的方法也面临着自己的问题：溶剂兼容性、复杂的反应、毒性以及难以将功能化粒子从剩余试剂和/或副产品中分离出来(这些问题在试图形成多功能表面时会变得复杂)。因此，目前的研究计划将重点放在不受这些限制的更多功能的气相纳米颗粒功能化方法上。具体地说，光引发的CVD将是首选的功能化工具，因为它在裁剪颗粒表面方面表现出了希望。这项工作预计将扩大我们对纳米颗粒进行功能化和定制的能力，并将对加拿大先进材料行业产生强大影响。

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.