Bespoke contrast-matched diblock copolymer nanoparticles enable the rational design of highly transparent Pickering double emulsions. Issue 30 (13th July 2016)

• Record Type: Journal Article
• Authors: Rymaruk, Matthew J.; Thompson, Kate L.; Derry, Matthew J.; Warren, Nicholas J.; Ratcliffe, Liam P. D.; Williams, Clive N.; Brown, Steven L.; Armes, Steven P.
• Is Part Of: Nanoscale. Volume 8:Issue 30(2016)
• Page Start: 14497
• Page End: 14506
• Publication Date: 2016-07-13
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c6nr03856e
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Contrast-matched diblock copolymer nanoparticles facilitate the production of highly transparent Pickering emulsions and Pickering double emulsions. Abstract : We report the preparation of highly transparent oil-in-water Pickering emulsions using contrast-matched organic nanoparticles. This is achieved via addition of judicious amounts of either sucrose or glycerol to an aqueous dispersion of poly(glycerol monomethacrylate)56 –poly(2, 2, 2-trifluoroethyl methacrylate)500 [PGMA–PTFEMA] diblock copolymer nanoparticles prior to high shear homogenization with an equal volume of n -dodecane. The resulting Pickering emulsions comprise polydisperse n -dodecane droplets of 20–100 μm diameter and exhibit up to 96% transmittance across the visible spectrum. In contrast, control experiments using non-contrast-matched poly(glycerol monomethacrylate)56 –poly(benzyl methacrylate)300 [PGMA56 –PBzMA300 ] diblock copolymer nanoparticles as a Pickering emulsifier only produced conventional highly turbid emulsions. Thus contrast-matching of the two immiscible phases is a necessary but not sufficient condition for the preparation of highly transparent Pickering emulsions: it is essential to use isorefractive nanoparticles in order to minimize light scattering. Furthermore, highly transparent oil-in-water-in-oil Pickering double emulsions can be obtained by homogenizing the contrast-matched oil-in-water Pickering emulsion prepared using the PGMA56 –PTFEMA500 nanoparticles with a contrast-matched dispersion of hydrophobic poly(lauryl methacrylate)39 –poly(2, 2, 2-trifluoroethyl methacrylate)800 [PLMA39 –PTFEMA800 ] diblock copolymer nanoparticles in n -dodecane. Finally, we show that an isorefractive oil-in-water Pickering emulsion enables fluorescence spectroscopy to be used to monitor the transport of water-insoluble small molecules (pyrene and benzophenone) between n -dodecane droplets. Such transport is significantly less efficient than that observed for the equivalent isorefractive surfactant-stabilized emulsion. Conventional turbid emulsions do not enable such a comparison to be made because the intense light scattering leads to substantial spectral attenuation.