DIRECT OBSERVATION OF A DEFECT-MEDIATED VISCOELASTIC TRANSITION IN A HYDROGEL OF LIPID-MEMBRANES AND POLYMER LIPIDS

We present the first direct imaging of a new hydrogel of lipid membran es containing polymer lipids. Freeze-fracture electron microscopy show s unambiguously that the hydrogel's surprisingly large viscoelasticity is explained by a novel defect topology of interconnections between d efects. The defects are spherulites with high membrane curvatures whic h are either isotropic or cylinderlike. A lower concentration of dislo cation-type defects was also observed. The interconnections between th e defects distinguish the hydrogel from simple ''onion'' phases of mul tilamellar vesicles with a smaller viscoelasticity.