Probing and Modulating Interactions of Drops, Bubbles and Particles with Implications for Chemical Engineering Processes

加拿大拥有丰富的自然资源（如矿产、原油、原油沥青、天然气），对国民经济贡献巨大。液滴、气泡和固体颗粒在复杂流体环境中的相互作用，特别是在存在界面活性物质（如表面活性剂、聚合物、颗粒）的情况下，在决定自然资源生产中许多工程过程（如矿物浮选、沥青提取、油水分离、废水处理）的效率和性能方面起着关键作用。以往的研究主要集中在具有“清洁”界面（没有界面活性物质）的软材料和颗粒系统与具有均匀表面化学的固体基质之间的分子间和表面相互作用。然而，在实际工程应用中，界面活性物质广泛存在于固体/油/水/气界面和散装流体中，而许多固体表面在表面化学上表现出非均质性。在界面活性物质存在的情况下，这些可变形材料系统（如水滴、气泡）和具有表面非均质性的固体的相互作用力的量化更具挑战性，但具有基础和实际意义，这将是本研究的主要重点。该计划的长期目标是在纳米和微观尺度上阐明液滴、气泡和颗粒在界面活性物质（如表面活性剂、聚合物、纳米颗粒）存在下的物理化学性质和相互作用机制。短期目标是：(1)在界面活性物质存在的情况下，通过调节表面化学、纳米尺度非均质性、界面分子迁移率和水化学，量化液滴、气泡和固体颗粒在水介质中的分子间和表面作用力，并建立相互作用机制，特别是疏水相互作用；(2)阐明液滴的相互作用机制。具有光滑表面的气泡和固体颗粒，朝着具有水滴/气泡/颗粒可控运动操纵的新型光滑表面的发展。提出的研究将填补在界面活性物质存在下滴、泡和细固体的基本相互作用机制方面的知识空白，特别是对它们的分子间和表面力的量化，疏水相互作用的起源，以及疏水效应和其他表面力如何促进它们的相互作用行为（如组装、聚集和聚并）。拟议的研究还将为如何在相关工程过程中高效和有效地调节这些相互作用提供新的见解，并帮助开发新的材料和表面，以实现更有效的工业过程。研究成果将促进自然资源的可持续发展。

Canada has a vast wealth of natural resources (e.g., minerals, crude oil, crude bitumen, natural gas), contributing significantly to the national economy. The interactions of liquid drops, gas bubbles and solid particles in complex fluid environment, particularly in the presence interface-active species (e.g., surfactants, polymers, particles), play a critical role in determine the efficiency and performance of numerous engineering processes in natural resources production (e.g., mineral flotation, bitumen extraction, oil/water separation, wastewater treatment). Previous studies have mainly focused on the intermolecular and surface interactions of soft materials and particle systems with "clean" interfaces (without interface-active species) and solid substrates with homogeneous surface chemistry. In practical engineering applications, however, interface-active species are widely present at solid/oil/water/gas interfaces and in bulk fluids, while many solid surfaces show heterogeneity in surface chemistry. Quantifying the interaction forces of these deformable material systems (e.g., drops, bubbles) and solids with surface heterogeneity in the presence of interface-active species is much more challenging, but is of fundamental and practical importance, which will be the main focus of this proposed research. The long-term objective of this proposed program is to elucidate the physicochemical properties and interaction mechanisms of drops, bubbles and particles in the presence of interface-active species (e.g., surfactants, polymers, nanoparticles) at the nano- and micro-scale. The short-term objectives are to (1) quantify the intermolecular and surface forces and establish the interaction mechanisms, particularly hydrophobic interaction, of liquid drops, gas bubbles and solid particles in aqueous media, by modulating surface chemistry, nanoscale heterogeneity, interfacial molecular mobility and water chemistry, in the presence of interface-active species, and (2) elucidate the interaction mechanisms of liquid drops, gas bubbles and solid particles with slippery surfaces, towards the development of novel slippery surfaces with controlled motion manipulation of drops/bubbles/particles. The proposed research will fill the knowledge gap on the fundamental interaction mechanisms of drops, bubbles and fine solids in the presence of interface-active species, particularly on quantification of their intermolecular and surface forces, the origin of hydrophobic interactions, and how hydrophobic effects and other surface forces contribute to their interaction behaviors (e.g., assembly, aggregation, and coalescence). The proposed research will also provide new insights on how to efficiently and effectively modulate these interactions in related engineering processes and help develop new materials and surfaces towards more efficient industrial processes. The research outcomes will facilitate the sustainable development of natural resources.