Influence of amphiphilic block copolymers on lyotropic liquid crystals in water-oil-surfactant systems

Frank, C.; Sottmann, T.; Allgaier, J.; Stubenrauch, C.; Strey, R.

doi:10.1021/la051463r

Journal Article

PreJuSER-47569

Influence of amphiphilic block copolymers on lyotropic liquid crystals in water-oil-surfactant systems

Frank, C.FZJ* ; Sottmann, T. ; Stubenrauch, C. ; Allgaier, J.FZJ* ; Strey, R.

2005
ACS Publ. Washington, DC

Langmuir 21, 9058 - 9067 (2005) [10.1021/la051463r]

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Please use a persistent id in citations: http://hdl.handle.net/2128/1136 doi:10.1021/la051463r

Abstract: In ternary water-oil-nonionic alkyl polyglycol ether (C(i)E(j)) microemulsions, an increase in efficiency is always accompanied by the formation of a lamellar (L(alpha)) phase. The addition of an amphiphilic block copolymer to the ternary base system increases the efficiency of the microemulsion drastically while suppressing--at least partly--the formation of the L(alpha) phase. However, amphiphilic block copolymers can be used not only to suppress the formation of lyotropic liquid crystals but also for the opposite effect, namely, to induce their formation. To understand to what extent the increase in efficiency is accompanied by the formation of lyotropic liquid crystals, we studied phase diagrams of water-n-alkane-n-alkyl polyglycol ethers (C(i)E(j))-PEPX-PEOY at a constant volume fraction of oil in the water/oil mixture. Using polymers of the poly(ethylene propylene)-copoly(ethylene oxide) type, with M(PEP) = X kg mol(-1) and M(PEO) = Y kg mol(-1), we determined phase diagrams as a function of the polymer concentration, size, and symmetry. Moreover, the influence of a particular polymer mixture was studied, which turned out to be the best system if both a high efficiency and a low tendency to form an L(alpha) phase are needed.

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