Structure of partially fluorinated surfactant monolayers at the air-water interface.
Partially fluorinated cationic surfactants of the form C(n)F(2n+1)C(m)H(2m)N(CH3)Br have been prepared, and their behavior at the air-water interface has been studied using surface tension measurements and neutron reflectometry. The degree of fluorination has been varied while keeping the overall chain lengths similar. The results are compared with those previously obtained for C16H33N(CH3)Br (C16TAB). The structural studies show a decrease in molecular orientation with increasing fluorination. The mean tilt away from the surface normal varies from 55 degrees for C16TAB to 25 degrees for C8F17C6H12N(CH3)Br. The interfacial layer roughness is observed to be lower than that expected for a pure fluorocarbon surfactant.
Jackson
A J
AJ
Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, OX1 3QZ, UK. ajj@nist.gov
Li
P X
PX
Dong
C C
CC
Thomas
R K
RK
Penfold
J
J