Molecular origin of model membrane bending rigidity.
The behavior of the bending modulus kappa of bilayers in lamellar phases was studied by Small Angle X-ray Scattering technique for various nonionic C(i)E(j) surfactants. The bilayers are either unswollen and dispersed in water or swollen by water and dispersed in dodecane. For unswollen bilayers, the values of kappa decrease with both an increase in the area per surfactant molecule and in the polar head length. They increase when the aliphatic chain length increases at constant area per surfactant molecule. Whereas for water-swollen membranes, the values of kappa decrease as the content of water increases converging to the value of the single monolayer bending modulus. Such a behavior results from the decoupling of the fluctuations of the two surfactant membrane monolayers. Our results emphasize the determinant contribution of the surfactant conformation to kappa.
Laboratoire de Physique Statistique, Ecole Normale Supérieure de Paris, CNRS UMR8550, 24 rue Lhomond, 75005 Paris, France.
Erol
E
Kurtisovski
Nicolas
N
Taulier
Raymond
R
Ober
Marcel
M
Waks
Wladimir
W
Urbach
D004548:Elasticity; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D019563:Mechanics; D008567:Membranes, Artificial; D008956:Models, Chemical
D008051:Lipid Bilayers; D008567:Membranes, Artificial