Non-aqueous Isorefractive Pickering Emulsions

Abstract

Non-aqueous Pickering emulsions of 16–240 μm diameter have been prepared using diblock copolymer worms with ethylene glycol as the droplet phase and an n-alkane as the continuous phase. Initial studies using n-dodecane resulted in stable emulsions that were significantly less turbid than conventional water-in-oil emulsions. This is attributed to the rather similar refractive indices of the latter two phases. By utilizing n-tetradecane as an alternative oil that almost precisely matches the refractive index of ethylene glycol, almost isorefractive ethylene glycol-in-n-tetradecane Pickering emulsions can be prepared. The droplet diameter and transparency of such emulsions can be systematically varied by adjusting the worm copolymer concentration.

Polymerization-induced self-assembly of block copolymer nanoparticles via RAFT non-aqueous dispersion polymerization

“…Finally, Thompson et al just reported the preparation of non-aqueous Pickering emulsions [111]. In this case the water phase is replaced with ethylene glycol, which is immiscible with a wide range of n-alkanes.…”

“…Interestingly, judicious selection of an appropriate n-alkane with approximately the same refractive index as that of ethylene glycol enables the production of near-isorefractive emulsions. More specifically, emulsification of ethylene glycol (EG) with n-tetradecane using L 16 -B 37 worms dispersed in n-tetradecane produces almost transparent EG-in-n-tetradecane Pickering emulsions that exhibited up to 81% transmittance across the visible spectrum [111].…”

Radical polymerization of miniemulsions induced by compressed gases

“…39,40 It has been proposed that the transparency induced by compressed gases is related to the insertion of gas molecules into the interfacial lm, resulting in a change in the curvature and creating smaller droplets. 36 The transparent emulsion formed via CO 2 pressurization of TX-100 (poly(oxyethylene)iso-octylphenyl ether)/water/ isooctane at P T ¼ 3.90 MPa was characterized by small-angle Xray scattering (SAXS), yielding spherical droplets of diameter 92 nm.…”

Photopolymerization in dispersed systems

“…In a heterogeneous reaction system, the absorbed flux quantities depend on (vide supra) and the diminution of radiation due to forward-and back-scattering. The monochromatic incident photon flux 0 ( , ) at any point of an irradiated heterogeneous system may be calculated in applying the radiative transfer equation (RTE) [48,49] leading to…”