Pore formation and rupture in fluid bilayers

Structure and stability of fluid bilayers under stress are examined by modeling lipid as diblock copolymer and solvent as homopolymer. The model is solved using self-consistent field theory, and equilibrium phases are determined. We find that on increasing the stress applied to the bilayer, one of two scenarios occurs depending upon the architecture of the lipid. Either the bilayer ruptures, or pores form within it and condense into a regular array; In the former case, the fractional increase in area from its unstressed value is found to be approximately 2% at rupture, in satisfactory agreement with experiment. In the latter, the pores appear and disappear reversibly with the stress, in accord with experiment. We find the pores to be slightly hydrophobic.