Composite electrophoretic particles and variable transmission films containing the same

An electro-optic media comprising a polymeric sheet containing a plurality of sealed microcells, each microcell containing a dispersion, the dispersion comprising a plurality of charged composite particles and a suspending fluid, and the charged composite particles move through the suspending fluid under the influence of an electric field,

• wherein the composite particles comprise one or more pigment particles at least partially coated with a polymeric material, the pigment particles being selected from the group consisting of manganese ferrite black spinel, copper chromite black spinel, carbon black, and combinations thereof, and
• each of the polymeric sheet, the charged composite particles, and the suspending fluid have an index of refraction, and a difference between the index of refraction of the composite particles and the index of refraction of at least one of the suspending fluid and polymeric sheet is less than or equal to 0.05 at 550 nm.

An electro-optic media comprising a plurality of droplets in a continuous polymeric phase, each droplet containing a dispersion, the dispersion comprising a plurality of charged composite particles and a suspending fluid, and the charged composite particles move through the suspending fluid under the influence of an electric field,

• wherein the composite particles comprise one or more pigment particles at least partially coated with a polymeric material, the pigment particles being selected from the group consisting of manganese ferrite black spinel, copper chromite black spinel, carbon black, and combinations thereof, and
• each of the continuous polymeric phase, the charged composite particles, and the suspending fluid have an index of refraction, and a difference between the index of refraction of the composite particles and the index of refraction of at least one of the suspending fluid and continuous polymeric phase is less than or equal to 0.05 at 550 nm.