Gt. Raznikova et al., SURFACE-FILMS OF AN OVOMUCOID AT AN AIR-WATER-INTERFACE, Colloid journal of the Russian Academy of Sciences, 55(6), 1993, pp. 881-886
Studies are made of isotherms PI(A) (where PI is two-dimensional press
ure and A is the area per 1 mg of substance) of monolayers (ML) of an
ovomucoid (OM). The form of the isotherm depends on the amount of depo
sited protein c(s) and spreading time tsp. At c(s) > 1.7.10(-9) moles,
an inflection is seen on the isotherm with compression. The appearanc
e of this inflection is connected with collapse of the structured mono
layer. At c(s) < 1.7.10(-9) moles, the moles of the monolayer are unas
sociated molecules of an ovomucoid, while quarternary structures of a
cylindrical OM with a degree of association n = 3 and axial ratio 1:5
appear at c(s) > 1.7-10(-9) moles. The existence of the contricted sec
tion up to the points of inflection is due to the occurrence of liquid
-crystalline order and the appearance of a mononolecular nematic layer
. The estimated elastic modulus of the monolayer in compression approx
imately 20-25 mN/cm2 and the persistent particle length approximately
100 angstrom. Relaxation of PI was studied at PI > PI(c) for ovomucoid
film with a compressed layer of constant area due to the nucleation o
f a bulk phase. Subsequent expansion of the monolayer was accompanied
by the appearance of a hysteresis loop, which is connected with the sp
reading of bulk segments of the nematic into the monolayer.