Generation of Polymerosomes from Double-Emulsions

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Original entry: Pratomo Putra (Tom) Alimsijah, APPHY 226, Spring 2009

Generation of Polymerosomes from Double-Emulsions

Elise Lorenceau, Andrew S. Utada, Darren R. Link, Galder Cristobal, Mathieu Joanicot, and David A. Weitz, Langmuir 21, 9183-9186 (2005).

Soft Matter Keywords

Ampiphilic, capillaries, hydrophobic, Rayleigh-Plateau instability, polymerosomes, emulsions, hydrophobic, micelles

Abstract

(From paper) Diblock copolymers are known to spontaneously organize into polymer vesicles. Typically, this is achieved through the techniques of film rehydration or electroformation. We present a new method for generating polymer vesicles from double emulsions. We generate precision water-in-oil-in-water double emulsions from the breakup of concentric fluid streams; the hydrophobic fluid is a volatile mixture of organic solvent that contains dissolved diblock copolymers. We collect the double emulsions and slowly evaporate the organic solvent, which ultimately directs the self-assembly of the dissolved diblock copolymers into vesicular structures. Independent control over all three fluid streams enables precision assembly of polymer vesicles and provides for highly efficient encapsulation of active ingredients within the polymerosomes. We also use double emulsions with several internal drops to form new polymerosome structures.


Fig. 1 (A) Side and (B) front view of the device. The constriction has a radius a and three different fluids (f1, f2, f3) are forced to flow through it.

Soft Matter Discussion

The authors generated water-in-oil-in-water double emulsions using distilled water as the inner aqueous phase and a mixture of glycerol in distilled water (80% v/v). The intermediate phase used is a volatile organic solvent (poly(normal-butyl acrylate)-poly(acrylic acid)) in THF and toluene cosolvent mixture.


The glycerol in the outer fluid is important to increase viscosity and the efficiency of the flow focusing. The dissolved diblocks have to be unimers instead of larger aggregates to efficiently stabilize the inner droplet against coalescence with the outer phase and therefore preventing double emulsion break-up. THF has to be mixed with toluene to form a large enough interfacial tension with the aqueous phases. This will drive the Rayleigh-Plateau instability enabling the double emulsions.


Fig. 2 This figure shows the importance of having diblock copolymers. In part (A) where copolymer was added to f2, stable emulsions formed. However, in part (B) where no diblock copolymers were added, double emulsion break-up occurs.