Fluorosurfactants for microdroplets: Interfacial tension analysis

Quantitative analysis of a number of potential fluorous surfactants, prepared with a view to stabilisation of microdroplets in microfluidic systems is presented. The surfactants tested comprised compounds with both perfluoropolyether (PFPE) and perfluoroalkyl (PFA) tails, along with three classes of hydrophilic head group, including crown ethers and hexaethylene gylcol. Surfactants were tested for activity using the pendant drop technique. Six compounds proved highly effective and efficient surfactants, with γCMC < 10 mN/m and CMCs in the sub-millimolar range. These six compounds stabilised aqueous microdroplets in fluorous oils within poly(dimethylsiloxane) (PDMS) microdevices to a greater degree than commonly used pseudosurfactants such as perfluorooctanol.

Quantitative analysis of potential fluorosurfactant candidates and their use in formation of stable aqueous microdroplets in microfluidic environments.Figure optionsDownload high-quality image (93 K)Download as PowerPoint slideResearch highlights
► Performance of 12 novel fluorous surfactants quantified.
► Six compounds lower interfacial tension of aqueous-fluorous oil system to below 10 mN/m.
► A number of these compounds effective in producing stable aqueous microdroplets in fluorous oils.