Aligned stacks of monomethyl and dimethyl dimyristoyl phosphatidylethanolamine (DMPE) lipid bilayers, like the much studied dimyristoyl PC (DMPC) bilayers, swell anomalously in a critical fashion as the temperature is decreased within the fluid phase towards the main transition temperature, $T_M.$ Unlike DMPC bilayers, both monomethyl and dimethyl DMPE undergo transitions into a gel phase rather than a rippled phase below $T_M.$ Although it is not fully understood why there is anomalous swelling, our present results should facilitate theory by showing that the formation of the phase below $T_M$ is not related to critical phenomena above $T_M.$

• Received 2 August 2000

DOI:https://doi.org/10.1103/PhysRevE.63.030902