相关实验视频
Updated: May 30, 2026

10:56
Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
通过依赖形状的毛细血管相互作用抑制咖啡环效应.
Peter J Yunker1, Tim Still, Matthew A Lohr
1Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. pyunker@sas.upenn.edu
Nature
|August 19, 2011
概括
咖啡环效应,即颗粒沉积成环,可以通过使用圆形颗粒来消除. 颗粒形状控制沉积,允许均的涂层,而不改变颗粒或溶剂的化学成分.
科学领域:
- 物理 物理学 物理
- 材料科学 材料科学 材料科学
- 体科学 体科学 体科学
背景情况:
- 咖啡环效应描述了从干燥液滴中颗粒的环状沉积.
- 这种现象在各种颗粒大小和材料中很常见,阻碍了统一的涂层应用.
- 避免咖啡环效应的现有方法通常是复杂的或需要化学修改.
研究的目的:
- 研究粒子形状在液滴蒸发过程中控制沉积模式中的作用.
- 用粒子几何学来证明一种消除咖啡环效应的方法.
- 通过基于形状的控制来探索实现均颗粒沉积的潜力.
主要方法:
- 在固体表面液滴干燥的实验研究.
- 球形与圆形粒子沉积模式的比较.
- 分析空气-水界面上的粒子行为和粒子间相互作用.
主要成果:
- 圆形粒子与球体不同,在蒸发后会产生均的粒子沉积.
- 圆体的异型形状会引起强烈的粒子间毛细体相互作用和界面变形.
- 这些相互作用形成结构,防止粒子在落下边缘积聚.
- 球体和圆体的混合物也可以在特定条件下产生均沉积.
结论:
- 颗粒形状是控制干燥过程中沉积模式的关键参数.
- 使用圆形粒子提供了一种简单而有效的策略来克服咖啡环效应.
- 这种形状依赖的控制为在各种应用中创建均涂层提供了一种多功能方法.
相关概念视频
Rise of Liquid in a Capillary Tube
When very thin cylindrical tubes, called capillaries, are dipped in a liquid, the liquid rises or falls in the tube compared to the surrounding liquid. This phenomenon is called capillary action. Capillary action occurs due to the combination of two opposing forces: the cohesive forces of the liquid, which cause it to stick to itself and form a rounded shape, and the adhesive forces between the liquid and the walls of the container, which cause the liquid to be attracted to the container walls.
Capillarity in Fluid
Capillarity describes the movement of liquid in small spaces without external forces acting on it. The capillarity is driven by surface tension and adhesive interactions between the liquid and surrounding solid surfaces. This effect is often seen in narrow tubes, porous materials, and fine particles.
Surface tension is crucial to capillarity. It results from cohesive forces between liquid molecules at the liquid-air boundary, forming a skin that resists external forces. When the capillary tube...
Surface tension is crucial to capillarity. It results from cohesive forces between liquid molecules at the liquid-air boundary, forming a skin that resists external forces. When the capillary tube...
Surface Tension, Capillary Action, and Viscosity
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
Capillary Exchange
The cardiovascular system's chief role is to disseminate gases, nutrients, waste, and other substances to the body's cells. Small molecules like gases, lipids, and lipid-soluble substances directly diffuse through capillary wall endothelial cell membranes. Glucose, amino acids, and ions, including sodium, potassium, calcium, and chloride, use transporters for facilitated diffusion via membrane-specific channels. Glucose, ions, and bigger molecules may also pass through intercellular clefts.
Colloidal precipitates
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
Van der Waals Interactions
Atoms and molecules interact with each other through intermolecular forces. These electrostatic forces arise from attractive or repulsive interactions between particles with permanent, partial, or temporary charges. The intermolecular forces between neutral atoms and molecules are ion–dipole, dipole–dipole, and dispersion forces, collectively known as van der Waals forces.

