Facile fabrication of polymer/palygorskite microcapsules via pickering emulsion photopolymerization

A facile continuous flow Pickering emulsion photopolymerization process was developed to fabricate polymer/clay composite microcapsules. Photolatent Pickering emulsions of oil (monomer, crosslinker, Irgacure 819 and octane) in water were prepared using palygorskite fibers (PAL) as particulate emulsifier. Serials of factors on the formation of microcapsules have been investigated, such as PAL concentration, photoinitiator percentage, light intensity, crosslinker/monomer ratio and monomer type. Although the presence of higher PAL concentration provides the more stabile emulsion, 3 wt% of PAL offered the best condition to achieve polymer/PAL microcapsules by SEM observation. Further, it was found that 6 wt% of photoinitiator with 2 mW/cm² irradiation intensity provided the most suitable photopolymerization conditions for the formation of polymer/PAL microcapsules. Among different monomers, the one that formed polymer with suitable flexibility offered better formation of polymer/PAL spherical microcapsules. Additionally, the formation mechanism of the polymer/PAL microcapsules has been proposed.