142 research outputs found
Stabilization of tilt order by chain flexibility in Langmuir monolayers
Langmuir monolayers are modeled as systems of short chains, which are
confined to a planar surface at one end, but free to move within the plane. The
phase behavior is calculated in a mean field approximation, which combines the
self consistent field method with elements of classical density functional
theory. It is shown that phases with tilt order are unstable in systems of
stiff chains, but can be stabilized by chain conformational entropy in systems
of sufficiently flexible chains. The chain entropy is also responsible for the
appearance of an additional untilted phase, the liquid expanded phase. The
region of stability of the different phases is discussed, and their microscopic
structure is analyzed in some detail.Comment: to appear in Phys. Rev.
Phase Behaviour of Amphiphilic Monolayers: Theory and Simulation
Coarse grained models of monolayers of amphiphiles (Langmuir monolayers) have
been studied theoretically and by computer simulations. We discuss some of the
insights obtained with this approach, and present new simulation results which
show that idealised models can successfully reproduce essential aspects of the
generic phase behaviour of Langmuir monolayers.Comment: To appear in J. Phys.: Cond. Matte
Polyhedral vesicles
Polyhedral vesicles with a large bending modulus of the membrane such as the
gel phase lipid membrane were studied using a Brownian dynamics simulation. The
vesicles exhibit various polyhedral morphologies such as tetrahedron and cube
shapes. We clarified two types of line defects on the edges of the polyhedrons:
cracks of both monolayers at the spontaneous curvature of monolayer , and a crack of the inner monolayer at . Around the
latter defect, the inner monolayer curves positively. Our results suggested
that the polyhedral morphology is controlled by .Comment: 4 pages, 5 figure
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