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Metastability of a supercompressed fluid monolayer
Ethan C Smith1, Jonathan M Crane, Ted G Laderas
1Departments of Biochemistry, Oregon Health & Science University, Portland, Oregon 97239-3098, USA.
Biophysical Journal
|October 29, 2003
Summary
Monomolecular films of 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC) become metastable under rapid compression, exhibiting behaviors similar to the supercooling of liquids toward a glass transition.
Area of Science:
- Surface science
- Materials science
- Physical chemistry
Background:
- Monomolecular films of extracted calf surfactant collapse at equilibrium spreading pressure during quasi-static compressions.
- These films can become metastable at higher surface pressures when compressed faster than a threshold rate.
Purpose of the Study:
- To determine the mechanism by which monomolecular films of 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC) become metastable.
- To investigate the relationship between compression rate, surface pressure, and film collapse behavior.
Main Methods:
- Studied single-component POPC films.
- Performed quasi-static and rapid compressions at various surface pressures.
- Measured collapse rates and observed film behavior upon heating.
Main Results:
- Confirmed metastability of POPC films when compressed above a threshold rate.
- Observed a sharply defined maximum in collapse rate followed by a decrease at higher surface pressures.
- Found that rapidly compressed films recovered their ability to collapse upon heating without discontinuous area change.
Conclusions:
- The metastability of POPC films does not arise from a phase transition.
- The supercompression of POPC monolayers shares similarities with the supercooling of three-dimensional liquids towards a glass transition.