Preparation and characterization of polyurea microcapsules containing colored electrophoretic responsive fluid

A kind of yellow–red microencapsulated electronic ink was prepared by interfacial polymerization. The shell of the polyurea (PU) microcapsules was fabricated from tolyene 2,4-diisocyanate (TDI) and triethylene tetraamine (TETA). Pigment Hansa Yellow 10G, as negatively charged electrophoretic particles, was homodispersed in tetrachloroethylene (TCE)/cyclohexane mixture to make the suspending fluid core. And Oil Red was also added in the core to make a red background. Emulsifiers influencing the dispersing process were experimentally investigated. PU microcapsules were characterized on structure, mean particle size and size distribution, morphology with FT-IR, ESEM and image analyzer. The prepared microcapsules were regular, transparent, smooth and optically clear, and had a wall thickness of around 1.5 μm and an excellent sealing property. The electric response behaviors of the electronic ink were studied under electrostatic field. The yellow particles moved quickly and reversibly inside the microcapsules while the electric field alternated, with a response time of 150 ms approximately at E = 30 V/mm.