Synthesis of functional microcapsules by in situ polymerization for electrophoretic image display elements

A new series of functional microcapsules were prepared by in situ polymerization technology with poly(urea–formaldehyde) as the shell material and two-phase suspensions as core materials. The suspensions were composed of the Benzidine Yellow pigment particles and the dielectric fluid of cyclohexane. The pigment particles were coated by polyethylene (PE) which was used as a charge control agent to present a modified surface chemistry for charging purpose, thus the charged particles could move reversibly toward positive electrode while providing an electric field. Accordingly, the obtained two-phase core/shell microcapsules could be considered as display elements to be used in electrophoretic image display. FE-SEM images and photographs of optical microscopy showed that the size and surface morphology of the microcapsule can be controlled by selecting different processing parameters.