- Date: 1882
- 1 : a surface forming a common boundary of two bodies, spaces, or phases <an oil-water interface>
- 2 a : the place at which independent and often unrelated systems meet and act on or communicate with each other <the man-machine interface>
- b : the means by which interaction or communication is achieved at an interface
An interface is a surface forming a common boundary among two different phases, such as an insoluble solid and a liquid, two immiscible liquids or a liquid and an insoluble gas. The importance of the interface depends on which type of system is being treated: the bigger the quotient area/volume, the more effect the surface phenomena will have. Therefore interfaces will be considered in systems with big area/volume ratios, such as colloids.
Interfaces can be spherical or flat, so they can be considered to be always spherical with finite or infinite radius. For example oil droplets in a salad dressing are spherical but the interface between water and air in a glass of water is mostly flat.
One important interface is the gas liquid interface between aerosols and other atmospheric molecules.