Study of phase separation and critical phenomena of micellar solutions by laser light scattering

Abstract

Laser light scattering was performed to understand the composition effects of PEG-Lipids(PEG-DMPE) and Lipids(DMPC) on the phase separation and critical phenomena of micellar solutions. The scattering intensity (Ⅰ) and correlation length(ξ) were measured by static and dynamic light scattering as a function of temperature and composition. The scattering intensity and the correlation length diverge as temperature approaches a phase separation temperature ($T_{sp}$). The critical exponents (γ, ν) represent that the temperature dependence of I and ξ agrees with values of theoretical critical indices (γ=1.2, ν=0.6) in a three dimension. Furthermore, $T_{sp}$ strongly depends on the composition of the PEG-DMPE and DMPC, and can be understood by introducing the intermicellar interaction energy.