Monodisperse macroporous microspheres prepared by microfluidic methods and their oil adsorption performance

[Display omitted] •Monodisperse microporous microspheres are prepared by microfluidic methods.•The number and diameter of pores in the microspheres can be controlled by adjusting the porogen quantity.•The microporous microspheres have excellent adsorption capacity and long-term reusability for removal of oil from aqueous solution. Monodisperse macroporous poly(methyl methacrylate- hydroxyethyl methacrylate) (poly(MMA-HEMA)) microspheres have been successfully prepared by microfluidic methods. In our experiment, numerous fine water droplets were at first fabricated by homogeneous emulsification method and were then evenly dispersed inside monodisperse poly(MMA-HEMA) microspheres as porogens by using a combination of the microfluidic emulsification and the free-radical polymerization method. The embedded fine water droplets within the poly(MMA-HEMA) microspheres resulted in highly controllable uniform porous structures. Fourier transform infrared (FT-IR) spectrometer and scanning electron microscopy (SEM) were employed to examine the chemical compositions and microstructures of the microspheres. The effects of porogen quantity on the macroporous structures have been investigated systematically. The macroporous microspheres samples showed superior adsorption performance. With a water-in-oil type emulsion (water-to-oil volume ratio = 40%) used as the porogen, the microporous microspheres adsorbed 3.18 and 2.80 times their own weight of oil in diesel and in ethylene glycol dimethacrylate (EGDMA), respectively, and the adsorption capacity of microspheres remained unchanged by repeating the process five times. The large adsorption capacity for oil and good reusability of the macroporous microspheres make them attractive when applied in the separation of water and oil.