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The diffusion of colloids, nanoparticles, and small molecules near the gas–liquid interface presents interesting multiphase transport phenomena and unique opportunities for understanding interactions near the surface and interface. Stratification happens when different species preside over the interfaces in the final dried coating structure. Understanding the principles of stratification can lead to emerging technologies for materials’ fabrication and has the potential to unlock innovative industrial solutions, such as smart coatings and drug formulations for controlled release. However, stratification can be perplexing and unpredictable. It may involve a complicated interplay between particles and interfaces. The surface chemistry and solution conditions are critical in determining the race of particles near the interface. Current theory and simulation cannot fully explain the observations in some experiments, especially the newly developed stratification of nano-surfactants. Here, we summarize the efforts in the experimental work, theory, and simulation of stratification, with an emphasis on bridging the knowledge gap between our understanding of surface adsorption and bulk diffusion. We will also propose new mechanisms of stratification based on recent observations of nano-surfactant stratification. More importantly, the discussions here will lay the groundwork for future studies beyond stratification and nano-surfactants. The results will lead to the fundamental understanding of nanoparticle interactions and transport near interfaces, which can profoundly impact many other research fields, including nanocomposites, self-assembly, colloidal stability, and nanomedicine.
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This content will become publicly available on July 31, 2026
Chemistry & Photochemistry on Interfaces
When we think of a chemical process, we typically envision it occurring in the bulk phase of a system, leaving the interface overlooked. However, the chemistry at the surface can be significantly different from what happens in the bulk. As we scale down—considering water droplets in a cloud, mineral dust particles in the atmosphere, or the surface of a crystal exposed to reactive gases—the surface area becomes much more prominent than the bulk. Conversely, when considering larger systems, like the oceans or a planet's surface, it becomes evident that interfaces play a crucial role in chemical processes. Chemistry at surfaces and interfaces is pervasive, impacting many scientific fields. Surface chemistry and photochemistry are essential for understanding and controlling the processes at these interfaces. These disciplines are key to natural phenomena and technological advancements by revealing how molecules interact and transform at boundaries. Surface chemistry uncovers the unique behaviors of surface atoms and molecules, which experience unbalanced forces and higher free energies compared to their counterparts in the bulk. This distinctive reactivity drives adsorption, surface tension, and heterogeneous catalysis. In this primer, the authors explore the fundamental phenomena and core concepts shaping chemistry and photochemistry at interfaces. Each chapter examines a specific aspect of interface chemistry; however, reading the entire primer is recommended to gain a thorough understanding of the material. Whether you're a student beginning research in this area or seeking a deeper understanding of these complex dynamics, we hope this primer is a valuable resource for your future work.
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- Award ID(s):
- 2003814
- PAR ID:
- 10654731
- Publisher / Repository:
- American Chemical Society
- Date Published:
- ISBN:
- 9780841295926
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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