Electrophoretic response of poly(methyl methacrylate) coated TiO2 nanoparticles

Abstract A microcapsule-based electronic ink display technique, which uses the microencapsulation of electrophoretic dispersion, is being developed for direct-view portable displays. Microcapsules of titanium dioxide (TiO 2 ) electrophoretic nanoparticle suspension were prepared using amino precondensates via in-situ polymerization. The amino prepolymers were synthesized from melamine-urea formaldehyde resin at 60 °C. However, since TiO 2 has a relatively high density (4.28 g/cm 3 ), the density mismatch causes severe sedimentation problem in the suspended media. In order to lower its density, TiO 2 was coated with poly(methyl methacrylate) via a dispersion polymerization method prior to being used for an electronic ink material. In order to improve their mobility, a charge control agent was also added to the suspension of synthesized nanoparticles in the dielectric medium. Electrophoretic mobility of the synthesized particles was investigated via electrophoretic light scattering. The morphology of the synthesized microcapsule was also characterized by optical microscopy, and scanning electron microscopy.

[1]  G. Choi,et al.  Effect of molar ratio of KOH to Ti-isopropoxide on the formation of BaTiO3 powders by hydrothermal method , 2003 .

[2]  N. Sottos,et al.  In situ poly(urea-formaldehyde) microencapsulation of dicyclopentadiene , 2003, Journal of microencapsulation.

[3]  H. Choi,et al.  Encapsulation of spherical iron-particle with PMMA and its magnetorheological particles , 2004, IEEE Transactions on Magnetics.

[4]  J. Jacobson,et al.  An electrophoretic ink for all-printed reflective electronic displays , 1998, Nature.

[5]  J. An,et al.  Preparation and characterization of titanium dioxide core/polymer shell hybrid composite particles prepared by emulsion polymerization , 2004 .

[6]  M. Dunky,et al.  Urea–formaldehyde (UF) adhesive resins for wood , 1998 .

[7]  H. Choi,et al.  Magnetorheological characterization of carbonyl iron based suspension stabilized by fumed silica , 2004 .

[8]  E. Sudoł,et al.  Encapsulation of inorganic particles via miniemulsion polymerization , 2000 .

[9]  Songyi Park,et al.  Melamine resin microcapsules containing fragrant oil: synthesis and characterization , 1999 .

[10]  J. An,et al.  Titanium dioxide core/polymer shell hybrid composite particles prepared by two-step dispersion polymerization , 2004 .

[11]  C. Kim,et al.  Amino Resin Microcapsules Containing Polystyrene-coated Electrophoretic Titanium Oxide Particle Suspension , 2003 .

[12]  B. Singer,et al.  The understanding and elimination of some suspension instabilities in an electrophoretic display , 1978 .

[13]  M. Jhon,et al.  Synthesis and electrorheological characteristics of microencapsulated conducting polymer , 2004 .

[14]  H. Choi,et al.  Magnetorheological Characterization of Polymer-Iron Composite Suspensions , 2004 .

[15]  M. Jhon,et al.  Synthesis and electrorheological characteristics of microencapsulated polyaniline particles with melamine-formaldehyde resins , 2001 .

[16]  H. Macholdt,et al.  Charge control agents and triboelectrically-adjusted pigments in electrophotographic toner , 1997 .

[17]  Sun Young Park,et al.  Polyaniline microsphere encapsulated by poly(methyl methacrylate) and investigation of its electrorheological properties , 2003 .

[18]  S. Jahromi.  The storage stability of melamine formaldehyde resin solutions: III. Storage at elevated temperatures , 1999 .