Dynamic Rheological Analysis of MLVs and lamellar phases in the system C12E4 / D2O

The mechanical properties of the lamellar phase, La, of the system C12E4/D2O were studied along an isoplethal path (30 wt% C12E4) in the temperature range 10 - 60°C. A dynamic analysis was determined by small strain oscil- latory rheometry. The multilamellar vesicles (“MLVs”) (“onions”) were transformed by shearing the lamellar phase. The micellar phase was investigated by steady and dynamic rheological experiments. The micellar aggre- gate size increases slightly upon heating and the transition from micelles to lamellae appears to be a first order transition. The mechanical spectra of the lamellar phase show a strong dependence of the moduli on the fre- quency. This is typical of defective lamellar phases. They are different from MLVs mechanical spectra. The MLVs viscous and storage moduli are almost independent from the frequency and they exhibit the characteristics of a strong gel. The temperature of formation of the MLVs phase influences the mechanical properties of the MLVs. Three different packing states of the MLVs phase were observed in the temperature range 25 - 55°C.