We have constructed a model for the kinetics of rupture of membranes under tension, applying physical principles relevant to lipid bilayers held together by hydrophobic interactions. The membrane is characterized by the bulk compressibility (for expansion) K and the thickness 2ht of the hydrophobic part of the bilayer. The model is a lattice model which incorporates stress relaxation, and considers the nucleation of pores at constant area, constant temperature, and constant particle number. The particle number is conserved by allowing multiple occupancy of the sites. A value for the rigidity of the phopholipid tails in the Lalpha liquid phase are found for saturated and unsaturated lipids, and long diblock copolymers. An equilibrium "phase diagram" is constructed as a function of temperature and strain with the pores total surface and distribution as the order parameters. With parameters relevant to saturated phosphatidylcholine (PC) lipid membranes, well defined regions of "no pores", "protopores (non-critical pores)", "rupture" are found. The model also reproduces recent results on super-thick membranes, and on membranes in presence of peptides. Free energy curves as a function of total pore surface are presented for various values of tension and temperature, and the fractal dimension of the pore edge is evaluated.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/6293 |
| Date | January 2002 |
| Creators | Fournier, Luc. |
| Contributors | Joos, Bela, |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 113 p. |
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