Hydrophilic modification of polymer microchannel for preparation of oil-in-water emulsions

Microchannel (MC) emulsification is a novel technique for preparing monodispersed emulsions. Recently, we fabricated a new type of MC plate using polymer materials instead of the silicon materials used for conventional MC emulsification, and reported that monodispersed water-in-oil (W/O) emulsions were successfully prepared using an acrylic polymer MC (PMC) plate with hydrophobic properties. In this study, we modified the PMC surface with poly-2-methacryloxyethyl phosphorylcholine butyl methacrylate (Lipidure-PMB) and poly-ethylvinylalcohol (Exceval) coatings by SiO2 spattering and SiO2 vacuum deposition before producing oil-in-water (O/W) emulsions. Experimental results showed that. the average droplet diameter and coefficient of variation were 35.7 mu m and 27.0% when the emulsion was prepared using a Lipidure-PMB coated PMC plate, with a polydispersed droplet diameter distribution; 24.3 mu m and 3.8% when prepared using an Exceval-coated PMC plate, with a monodispersed droplet diameter distribution; and 23.7 mu m and 4.2% when prepared using a SiO2 vacuum deposition PMC plate, also with a monodispersed droplet diameter distribution. When SiO2 spattering was used, however, the hydrophilic SiO2 film came off the plate surface during the emulsification process, and the channel was wetted by, the dispersed phase, with the result that preparation of a monodispersed O/W emulsion was impossible. Furthermore, we investigated the resistance to sonic treatment of modified PMC plates, and it was found that the PMC plate modified by SiO2 vacuum deposition demonstrated the strongest resistance to sonic treatment.