SOLUBILIZATION OF POLYMER IN THE LYOTROPIC LAMELLAR PHASE - THE AOT PEO/WATER SYSTEM/

The solubilization of a nonionic polymer, poly(ethylene oxide) (PEG), in a lamellar phase formed by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in water has been studied by H-2- and Na-23-NMR, small-angle X-r ay scattering (SAXS), and polarizing microscopy. It has been found tha t (i) a substantial amount of the PEO polymers can dissolve in the lam ellar phase, (ii) the solubilization of the polymers in the lamellar p hase diminishes with increasing molecular weight of the polymer, (iii) it is evident that the polymers are entrapped in the aqueous domains of the lamellar phase, and (iv) SAXS measurements indicate that the so lubilization of the PEO polymers in the lamellar phase exerts no appar ent influence on the width of the aqueous domain of the lamellar phase . In an attempt to further understand the experimental results, a simp le model of the stability of the lamellar phase based on a mean-field lattice theory and the Poisson-Boltzmann equation was used. The qualit ative results of the model were in line with the experimental data. Mo reover, it appeared that the electrostatic interaction is significant, and its coupling with nonelectrostatic contributions is important for the description of the solubilization of the PEO polymers in the lame llar phase formed by AOT in water.