On the coupling between membrane bending and stretching in lipid vesicles
The formation of a lipid vesicle from a lamellar phase involves a cost in bending energy of 100–1000 times the thermal energy for values of the membrane bending rigidity κ typical for phospholipid bilayers. The bending rigidity of a bilayer is however a strongly decreasing function of its thickness h, and the bilayer can thus reduce its bending energy by stretching (and thus thinning) the bilayer.
