Nonlinear Vibrational Probes of Structure at Charged Polymer-Aqueous Interfaces

聚合物被用于生产我们日常生活中遇到的许多物体，从汽车保险杠到洗发水瓶再到牙齿填充物。虽然这些材料的整体特性被调整，使它们坚硬或柔韧，透明或不透明，但同样的注意力也被用于调整它们的表面特性，以最好地与它们的预期环境相互作用。例如，丙烯酸等材料广泛用于制造医疗植入物，因为它们坚固且重量轻，但它们的表面不是天然生物相容的。 将聚合物表面暴露在一种称为等离子体的电离气体中，是科学家们改善体内丙烯酸和蛋白质之间相互作用的一种方法。但聚合物表面的性质并不是介导环境相互作用的唯一贡献者：与任何材料接触的水分子具有与本体水明显不同的性质。因此，水包围蛋白质的方式与聚合物表面的几纳米、几十到几百纳米的距离以及在本体水相中有很大的不同。因此，了解聚合物表面如何与水相互作用对于全面了解表面结构和粘附过程至关重要。 在所提出的计划中，我们使用高功率可见光和红外激光探测聚合物表面上发生的微观变化，以响应高压等离子体处理。然后，我们跟踪水分子在处理前后如何与表面相互作用的变化，以更好地了解聚合物的润湿特性如何改变。后续项目将引入氨基酸、肽和蛋白质等生物分子来表征其吸附结构，并巩固我们对这些复杂但基本的分子相互作用的理解。这一领域继续受到诸如球状蛋白质在疏水表面上变性的期望等概括性的阻碍。过去的五十年提供了许多例子，这是不正确的，指出需要一个详细的表面相互作用的分子水平的理解，从基板和溶剂。 这一领域的研究对生物医学工程师很重要，因为它为下一代医疗植入物涂层和表面处理提供了指导，或者为改进现有涂层和表面处理提供了思路。聚合物表面电荷改性在纺织品加工中非常重要，因为等离子体处理的纤维增加了对染料的粘附力，大大减少或消除了对工人和环境有害的溶剂的需求。研究带电聚合物表面还可以提高对轻质绝缘体如何承受风化的理解，从而为加拿大城镇提供可靠的架空配电。沿着，我们在这一领域的工作为下一代科学家和工程师提供了许多培训机会。

Polymers are used to produce many of the objects we encounter in our daily life, from car bumpers to shampoo bottles to dental fillings. While the bulk properties of these materials are tuned to make them stiff or pliable, transparent or opaque, an equal amount of attention goes into tailoring their surface properties to best interact with their intended surroundings. For example, materials such as acrylic are widely used in creating medical implants as they are strong and lightweight, but their surfaces are not naturally biocompatible. Exposing the polymer surface to an ionized gas called a plasma is one method by which scientists improve the interaction between acrylic and proteins in the body. But the nature of the polymer surface is not the sole contributor to mediating environmental interactions: water molecules in contact with any material have markedly different properties from bulk water. As a result, the way in which water surrounds proteins is vastly different a few nanometers from the polymer surface, tens to hundreds of nanometers away, and in the bulk water phase. Understanding how the polymer surface interacts with water is therefore critical to developing a holistic view of surface structure and adhesion processes. In the proposed program, we use high power visible and infrared lasers to probe microscopic changes that occur on the polymer surface in response to high-voltage plasma treatment. We then follow the change in how water molecules interact with the surface before and after treatment to better understand how the wetting characteristics of the polymer have been altered. Later projects will introduce biological molecules such as amino acids, peptides and proteins to characterize their adsorbed structure, and solidify our understanding of these complex but fundamental molecular interactions. The field continues to be hindered by generalizations such as the expectation for globular proteins to denature on hydrophobic surfaces. The past five decades have provided many examples where this is not true, pointing to the need for a detailed molecular-level understanding of surface interactions, starting with the substrate and the solvent. Research in this area is important to biomedical engineers as it provides guidance for the next generation of medical implant coatings and surface treatments, or ideas for improving existing ones. Polymer surface charge modification is important in textile processing, as plasma-treated fibres have increased adhesion to dyes, dramatically reducing or eliminating the need for solvents that are harmful for workers and the environment. Studying charged polymer surfaces also leads to improved understanding of how lightweight insulators withstand weathering for reliable overhead power distribution to Canadian towns and cities. Along the way, our work in this area provides many training opportunities for the next generation of scientists and engineers.