In-Channel Responsive Surface Wettability for Reversible and Multiform Emulsion Droplet Preparation and Applications.

摘要: We report on a simple approach for in-channel functionalization of polydimethylsiloxane (PDMS) surface to obtain switchable and reversible wettability change between hydrophilic hydrophobic states. The thermally responsive polymer, poly( N-Isopropylacrylamide) (PNIPAAm), was grafted the PDMS channels by UV-induced grafting. PNIPAAm-grafted (PNIPAAm-g-PDMS) can be tuned water contact angles varying in range 24.3 106.1° temperature at 25-38 °C. By selectively modifying functionalized area microfluidic channels, multiform emulsion droplets oil-in-water (O/W), water-in-oil (W/O), oil-in-water-in-oil (O/W/O), water-in-oil-in-water (W/O/W) could created on-demand. Combining solid liquid-liquid interfacial properties, tunable generation O/W W/O droplet stratified flows were enabled same device with either different or two-phase fluidic systems, properly heating/cooling thermal-responsive choosing suitable surfactants. Controllable creation O/W/O W/O/W also achieved device, locally heating cooling areas integrated electric heaters achieve opposite wettability. Hollow microcapsules prepared using double as templates sequential channel segments, demonstrating strength proposed practical applications.