View source for Interface (matter)

{{short description|Boundary between volumes of matter of different types or states}}
{{one source |date=March 2024}}
In the [[outline of physical science|physical sciences]], an '''interface''' is the boundary between two spatial regions occupied by different [[matter]], or by matter in different [[physical state]]s. The interface between matter and [[air]], or matter and [[vacuum]], is called a '''surface''', and studied in [[surface science]]. In [[thermal equilibrium]], the regions in contact are called [[phase (matter)|phases]], and the interface is called a [[phase boundary]]. An example for an interface out of equilibrium is the [[grain boundary]] in [[polycrystalline]] matter.
The importance of the interface depends on the type of system: the bigger the quotient area/volume, the greater the effect the interface will have. Consequently, interfaces are very important in systems with large interface area-to-volume ratios, such as [[colloid]]s.
Interfaces can be flat or curved. 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.
[[Surface tension]] is the physical property which rules interface processes involving liquids. For a liquid film on flat surfaces, the liquid-vapor interface keeps flat to minimize interfacial area and system [[Thermodynamic free energy|free energy]]. For a liquid film on rough surfaces, the [[surface tension]] tends to keep the [[Meniscus (liquid)|meniscus]] flat, while the [[disjoining pressure]] makes the film conformal to the substrate. The equilibrium meniscus shape is a result of the competition between the [[capillary pressure]] and disjoining pressure.<ref>{{cite journal | last1=Hu | first1=Han | last2=Weinberger | first2=Christopher R. | last3=Sun | first3=Ying|author3-link=Ying Sun (mechanical engineer) | title=Effect of Nanostructures on the Meniscus Shape and Disjoining Pressure of Ultrathin Liquid Film | journal=[[Nano Letters]] | publisher=American Chemical Society (ACS) | volume=14 | issue=12 | date=2014-11-17 | issn=1530-6984 | doi=10.1021/nl5037066 | pages=7131–7137| pmid=25394305 | bibcode=2014NanoL..14.7131H }}</ref>
Interfaces may cause various [[optical phenomena]], such as [[refraction]].  [[Lens (optics)|Optical lenses]] serve as an example of a practical application of the interface between [[glass]] and air.
One topical interface system is the gas-liquid interface between [[aerosols]] and other atmospheric molecules.
==See also==
* [[Capillary surface]], a surface that represents the boundary between two fluids
* [[Disjoining pressure]]
* [[Free surface]]
* [[Interface and colloid science]]
* [[Membrane (disambiguation)]]
* [[Surface phenomenon]]
==References==
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{{DEFAULTSORT:Interface (Chemistry)}}
[[Category:Colloidal chemistry]]
[[Category:Matter]]
[[Category:Surface science]]
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