Synthesis and characteristics of microcapsules containing electrophoretic particle suspensions

A microcapsule containing titanium dioxide (TiO2) and halocarbon oil was synthesized via an in situ polymerization using urea, melamine, and formaldehyde (UM/F) as a wall material to examine its potential application as a microcapsule-based electronic ink display technique. Poly(sodium styrene sulfonate) was used as an anionic polymeric surfactant to stabilize a droplet of the suspension, and easily combined with the UM/F prepolymer through ionic adsorption. The microcapsules obtained had an average diameter and wall thickness of approximately 50 μm and 500 nm, respectively. The electrophoretic TiO2 particles in the microcapsules responded to electric fields with a response time of few seconds.