Surface Pressure Isotherm

The difference between the surface tension on a clean liquid surface and surface tension in the presence of amphiphiles floating on the surface is termed the surface pressure. It is measured in the same units as surface tension. A graph relating the surface pressure to the area occupied by the amphiphiles at various states of compression is called a surface pressure isotherm. It may be used to characterize the conformational changes which molecules undergo upon "2-dimensional" compression. This information is useful to researchers...                         For more on theory click this link.

Methods of surface pressure isotherm production

Langmuir film balance

Certain amphiphilic molecules can form insoluble monolayers floating on a subphase. If such molecules are placed on a Langmuir trough a compression of the trough surface area may be performed. Using a Wilhelmy plate placed in the surface, surface pressure can be measured. A graph of surface pressure vs surface area( either absolute area or mean molecular area) is produced.                                                  For more on Langmuir balance click this link.

Instruments which can be used to produce surface pressure isotherms:

KSV 5000

KSV 3000

KSV 2000

KSV Minitrough

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