Investigations of the dynamic behavior of fatty acid monolayers at the air–water interface using a displacement current‐measuring technique coupled with the Langmuir‐film technique

1991 ◽  
Vol 94 (7) ◽  
pp. 5135-5142 ◽  
Author(s):  
Mitsumasa Iwamoto ◽  
Yutaka Majima
Keyword(s):  
Fatty Acid ◽  
Dynamic Behavior ◽  
Measuring Technique ◽  
Displacement Current ◽  
Water Interface ◽  
Langmuir Film ◽  
Air Water Interface ◽  
Current Measuring

Metastability in Monolayer Films Transferred onto Solid Substrates by the Langmuir-Blodgett Method: IR Evidence for Transfer-Induced Phase Transitions

1994 ◽  
Vol 48 (10) ◽  
pp. 1196-1203 ◽  
Author(s):  
Fazale R. Rana ◽  
Suci Widayati ◽  
Brian W. Gregory ◽  
Richard A. Dluhy
Keyword(s):  
Fatty Acid ◽  
Conformational Changes ◽  
Structural Changes ◽  
High Surface ◽  
Solid Substrate ◽  
Water Interface ◽  
Monolayer Films ◽  
Langmuir Blodgett ◽  
Monomolecular Film ◽  
Air Water Interface

The rate at which a monomolecular film is deposited onto a solid substrate in the Langmuir-Blodgett process of preparing supported monolayer films influences the final structure of the transferred film. Attenuated total reflectance infrared spectroscopic studies of monolayers transferred to germanium substrates show that the speed at which the substrate is drawn through the air/water interface influences the final conformation in the hydrocarbon chains of amphiphilic film molecules. This transfer-induced effect is especially evident when the monolayer is transferred from the expanded region of surface-pressure-molecular-area isotherms at low surface pressures; the effect is minimized when the film molecules are transferred from condensed phases at high surface pressures. This phenomenon has been observed for both a fatty acid and a phospholipid, which suggests that these conformational changes may occur in a variety of hydrocarbon amphiphiles transferred from the air/water interface. This conformational ordering may be due to a kinetically limited phase transition taking place in the meniscus formed between the solid substrate and aqueous subphase. In addition, the results obtained for both the phospholipid and fatty acid suggest that the structure of the amphiphile may help determine the extent and nature of the transfer-speed-induced structural changes taking place in the monomolecular film.

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