Student Poster Presentation # 1 ( Session 1 ) Stable Pickering Emulsions Using Janus Particles via Microfluidics
Student Poster Presentation # 1 ( Session 1 ) Stable Pickering Emulsions Using Janus Particles via Microfluidics
Bobby Haney , Liheng Cai , Dong Chen , David A . Weitz , Subramanian Ramakrishnan Department of Chemical and Biomedical Engineering , FAMU-FSU College of Engineering , 2525 Pottsdamer St , Tallahassee , Florida 32310
Abstract
Stable Pickering emulsions are important to systems where controlled confinement of an oil or water phase are critical to its applications . The stability of the Pickering emulsions depend on the wetting properties of the particle . For this reason amphiphilic “ Janus ” particles have proven to be major assets in forming stable Pickering emulsions . The key to forming either o / w or w / o emulsions depends on the ratio of lengths of the hydrophobic to hydrophilic parts .
Polyethylene Glycol diacrylate ( PEGDA ), ethoxilated trimethylopropane triacrylate ( ETPTA – monomer to be polymerized ), 2-hydroxy-2-methyl-propiophenone ( HMP – photo initiator ), and water were mixed together to form the hydrophilic portion of the inner-phase . 99 wt % trimethylopropane triacrylate ( TMPTA ) and 1 wt % 2- hydroxy-2-methyl-propiophenone were added together to form the hydrophobic portion of the inner-phase . HMP would serve as the photo-initiator for polymerization under UV light . 95 wt % silicone oil ( viscosity of 20 centi stokes ) and 5 wt % Dow Corning Resin 749 , as the surfactant served as the continuous phase . Janus particles were formed using flow of these solutions in a glass capillary microfluidic device . Flowrates were varied to control particle sizes ( 125- 400 microns ) and hydrophilic to hydrophobic domain volume ratios ( 0.14 – 7 ). At a fixed surfactant concentration , variations of the ratio of inner water to oil flow rates lead to the formation of amphiphilic embedded particles of different sizes and hydrophobic portions . Using UV light , these droplets were cross-linked via photo-polymerization to form fairly monodispersed particles . The size of the emulsions were controlled by changing the size of the Janus particles .
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