Amphiphilic Block Copolymers as Efficiency Boosters for Microemulsions

Abstract

We demonstrate that block copolymers of the poly(ethylenepropylene)-co-poly(ethylene oxide) (PEP−PEO) type dramatically enhance the solubilization capacity of medium-chain surfactants in microemulsions, for example, in the ternary system water−n-decane−C10E4. The effect exhibits itself in an enormous increase of the swelling of the middle phase with an associated increase in the structural length scale of the microemulsion, while at the same time the (already ultralow) interfacial tension between water- and oil-rich phases decreases even further. Typically, the surfactant mass fraction γ0 = 0.13 sufficient to form the balanced one-phase microemulsion in the ternary system can be replaced by γ = 0.035 of surfactant plus polymer. If δ is the polymer mass fraction in the surfactant/polymer mixture, the overall mass fraction of polymer in the microemulsion amounts only to γδ = 0.004. Accordingly, in this example the polymer is f B = 24 times more efficient than the surfactant, where we define an efficiency boost factor by f B = (γ0 − γ(1 − δ))/γδ. The magnitude of the effect depends to some extent on the overall molar mass of the polymer but rather weakly on the relative size of the hydrophilic and hydrophobic blocks. Interestingly, the lamellar phase, which usually develops as surfactants become more efficient, is suppressed.

Development of Novel Cosmetic Base Using Sterol Surfactant. II. Solubilizing of Sparingly Soluble Ultraviolet Ray Absorbers^†

“…Therefore, it was suggested that EPDME(14/7) enhanced the solubilizing ability of PO7/EO30-PS for BEMT. A previous study has reported a similar result; the solubilization quantity of oil increased when a polyoxyethylene/polyoxypropylene block co-polymer was used as a booster 19,20) . Moreover, even a phytosterol surfactant having lowest hydrophilicity, such as PO20/EO20-PS, showed a higher solubilizing ability than EO30-PS, when BEMT was solubilized by the preparation method with EPDME(14/7) ( ).…”

New Trends on the Synthesis of Inorganic Nanoparticles Using Microemulsions as Confined Reaction Media

“…In addition, nonionic surfactants have a great capacity of hydration by their ethoxylated (EO) units; hence, an appropriate selection of surfactant, oil and precursor salts/precipitating agent concentration, in combination with the rich structural behavior that such a system may display as a function of temperature, can lead to highly optimized formulations in terms of aqueous phase uptake and hence reactants loading. A good premise to this behavior is the enormous efficiency boost in the formation of middle phase microemulsions by the use of block copolymer surfactants reported by Strey et al (Jakobs et al, 1999).…”

Development of Novel Cosmetic Base Using Sterol Surfactant. I. Preparation of Novel Emulsified Particles with Sterol Surfactant+

“…glyceryl tri(2-ethylhexanoate) and di(2-ethylhexyl) succinate) and water. On the other hand, because EPDME is a random copolymer and differs from a block copolymer that cam make micelle structure in water [12][13][14][15][16] , EPDME is unable to form self-assemble structure by itself.…”