| 초록 |
We investigate the association of an amphiphilic polymer (PEG-DMPE) into a lamella phase formed from cationic (CTAT) - anionic (SDBS) surfactant mixtures using cryo-TEM, FF-TEM and small angle x-ray scattering. Freeze-fracture EM results unambiguously show that addition of a small amount of PEG-lipid to these swollen lamellar phases induces interconnected high curvature defects and lead to gelation, indicating a low bending modulus of the catanionic surfactant bilayer. From the measurement of the bilayer bending modulus via the vesicle size distribution determined from cryo-TEM, we find the CTAT/SDBS alone have a very low bending rigidity (K~0.4kBT), indicating that steric undulations stabilize the lamellar phases. Thus, gelation of catanionic surfactant system mostly resulted from highly fluctuating membrane in low bending modulus, which leads to the proliferation of interconnected, high curvature defects. The gel-like morphology was not observed in a stiff catanionic bilayer, CTAB/FC8, having high bending (K~6kBT) modulus.
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