Krytox157 fsh

We used aqueous droplets in Novec7500 fluorinated oil (3M) stabilized against coalescence by a triblock copolymer fluorosurfactant comprising two perfluoropolyether (PFPE) chains linked by one Jeffamine^® polyetheramine chain (PEA), KryJeffD₉₀₀. KryJeffD₉₀₀ surfactant was prepared in house from the commercially available carboxylic acid Krytox157-FSH (Dupont) and Jeffamine^® polyetheramine (ED 900, Huntsmann) based on the synthesis route described in23 (link)43 (link). Briefly, Krytox157-FSH (50 g; 7.8 mmol assuming 6500 g.mol⁻¹) was dissolved in 150 ml of CaCl₂ dried Novec7100 oil under a N₂ atmosphere. Next, oxalyl chloride (7.7 ml; 90 mmol) was added dropwise and the mixture stirred overnight at 70 °C. After evaporating the solvent, the resulting product was dissolved in 100 ml of FC-3283 oil (3M). Jeffamine^® polyetheramine (3.3 ml; 7.9 mmol), 20 ml of dried tetrahydrofuran, thriethylamine (1.6 ml; 11.5 mmol) and 40 ml of dried tetrahydrofuran were subsequently added in a twin-neck round-bottom flask under a N₂ atmosphere. The Krytox157-FSH acid chloride solution was added in the flask, followed by 20 ml of FC-3283 oil (3M). The mixture was stirred overnight at room temperature. After removing the solvents and purification by filtration, the product was used directly in the experiments.