Difference between revisions of "Wetting"

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[[Skating on a Film of Air: Drops Impacting on a Surface]]
[[Skating on a Film of Air: Drops Impacting on a Surface]]
[[Cationic liposome–microtubule complexes: Pathways to the formation of two-state lipid–protein nanotubes with open or closed ends]]

Revision as of 18:07, 1 October 2012

Written by Grant England AP225, Fall 2011


Wetting refers to how well or poorly a liquid contacts a surface. Usually the term applies to water, where if a surface is hydrophobic it will not wet well while if it is hydrophilic it will wet well. The relative hydrophobicity or hydrophilicity of a substrate can be determined by measuring the contact angle of water with the surface. A liquid wets a surface better if it has a low contact angle with that surface. In general, if the contact angle is lower than 90 degrees, the liquid is considered to be wetting for that surface; while, if the contact angle is greater than 90 degrees, the liquid is non-wetting for the surface.

Diagram showing states for a liquid on a surface with (A) little wetting, (B) moderate wetting, and (C) high wetting. (Taken fromWikipedia Article )

Cassie and Wenzel States

Surfaces can be made to be superhydrophobic or superhydrophilic by modification to have high aspect-ratio structures (micro-posts) on their surfaces, and chemical modification of these surfaces with hydrophobic or hydrophilic functional groups. Depending on the energetics of the surface, a drop of liquid on such a surface can be in either of two states--sitting on top of the micro-posts or sitting with the micro-posts embedded within it. The former is the Cassie state and the latter is the Wenzel state.

Ways to Change Wetting

Surfactants can change the wetting properties of a liquid, since they change the energetics of the surface of the liquid. Also, changing the properties of the surface by chemical functionalization or modification of the surface (etching or other methods of attaining high aspect-ratio structures on the surface which increase the microscopic surface area) can change a liquid-solid interaction from wetting to non-wetting or vice versa.

See also

Wetting from Lectures for AP225.



Aizenberg Lab @Harvard: Wettability

Wikipedia Article

Keyword in references:

Controlled switching of the wetting behavior of biomimetic surfaces with hydrogel-supported nanostructures

Critical Casimir effect in three-dimensional Ising systems: Measurements on binary wetting films

Dewetting-Induced Membrane Formation by Adhesion of Amphiphile-Laden Interface

Encoding complex wettability patterns in chemically functionalized 3D photonic crystals

Pitcher plant inspired non-stick surface

Structural Transformation by Electrodeposition on Patterned Substrates (STEPS) - A New Versatile Nanofabrication Method

Enriching libraries of high-aspect-ratio micro- or nanostructures by rapid, low-cost, benchtop nanofabrication

Steering nanofibers: An integrative approach to bio-inspired fiber fabrication and assembly

Fine-Tuning the Degree of Stem Cell Polarization and Alignment on Ordered Arrays of High-Aspect-Ratio Nanopillars

Screening Conditions for Rationally Engineered Electrodeposition of Nanostructures (SCREEN): Electrodeposition and Applications of Polypyrrole Nanofibers using Microfluidic Gradients

Combinatorial Wetting in Colour: An Optofluidic Nose

Elastic Instability in Growing Yeast Colonies

Liquid-infused structured surfaces with exceptional anti-biofouling performance

Liquid-Infused Nanostructured Surfaces with Extreme Anti-Ice and Anti-Frost Performance

Wetting in Color: Colorimetric Differentiation of Organic Liquids with High Selectivity

Electric-field-induced capillary attraction between like-charged particles at liquid interfaces

Dynamics of foam drainage

Dynamic mechanisms for apparent slip on hydrophobic surfaces

Linear stability and transient growth in driven contact lines

Spreading of Droplets on a Solid Surface

The single-cell chemostat: an agarose-based, microfluidic device for high-throughput, single-cell studies of bacteria and bacterial communities

DNA molecules and configurations in a solid- state nanopore microscope

Graphene as a subnanometre trans-electrode membrane

Non-stick water

How aphids lose their marbles

Elasticity of an interfacial particle raft

Nested self-similar wrinkling patterns in skins

The ‘‘Cheerios effect’’

Soft lubrication: The elastohydrodynamics of nonconforming and conforming contacts

Capillary rise between elastic sheets

Dynamics of Surfactant-Driven Fracture of Particle Rafts

Mechanics of Interfacial Composite Materials

The Universal Dynamics of Cell Spreading

Localized and extended deformations of elastic shells

Self-Organization of a Mesoscale Bristle into Ordered, Hierarchical Helical Assemblies

Hygromorphs: from pine cones to biomimetic bilayers

Infochemistry: Encoding Information as Optical Pulses Using Droplets in a Microfluidic Device

Control of Shape and Size of Nanopillar Assembly by Adhesion-Mediated Elastocapillary Interaction

How wet paper curls

Shock-driven jamming and periodic fracture of particulate rafts

Hydrodynamics of Writing with Ink

Skating on a Film of Air: Drops Impacting on a Surface

Cationic liposome–microtubule complexes: Pathways to the formation of two-state lipid–protein nanotubes with open or closed ends