Experimental Study of Water-in-Oil Emulsion Generation Using a Microfluidic Chip

The work presents the results of experimental studies aimed at developing methods and conditions for emulsion formation using a microfluidic chip. To establish a regime map for the generation of stable emulsions, a wide range of inlet pressure values for both the continuous (aqueous) and dispersed hydrocarbon phases was systematically tested. Emulsions were produced both without the use of an emulsifier and with the addition of 0,5 wt% of the surfactant polysorbate 80 to the aqueous phase. It was demonstrated that incorporation of polysorbate 80 significantly reduces coalescence of hydrocarbon phase droplets, thereby promoting the formation of stable emulsions. Hydrophilization of the microfluidic chip channel walls was carried out via plasma surface activation followed by treatment with polyvinyl alcohol. This modification in surface wettability markedly improved the conditions for generating stable emulsions with a near-monodisperse droplet size distribution. As a result of systematic experiments, the pressure ranges in which such emulsions are formed were identified. Surface hydrophilization was found to significantly expand the parameter range for the generation of stable emulsions.