Elastic Property of Membranes Self-assembled from Diblock and Triblock Copolymers
Abstract
The elastic property of membranes self-assembled from AB diblock and ABA
triblock copolymers, as coarse-grained model of lipids and the bolalipids, are
studied using the self-consistent field theory (SCFT). Specifically, solutions
of the SCFT equations, corresponding to membranes in different geometries
(planar, cylindrical, spherical, and pore) have been obtained for a model
system composed of amphiphilic AB diblock copolymers and ABA triblock
copolymers dissolved in A homopolymers. The free energy of the membranes with
different geometries is then used to extract the bending modulus, Gaussian
modulus, and line tension of the membranes. The results reveal that the bending
modulus of the triblock membrane is greater than that of the diblock membrane.
Furthermore, the Gaussian modulus and line tension of the triblock membrane
indicate that the triblock membranes have higher pore formation energy than
that of the diblock membranes. The equilibrium bridging and looping fractions
of the triblock copolymers are also obtained. Implications of the theoretical
results on the elastic properties of biologically equivalent lipid bilayers and
the bolalipid membranes are discussed.