Electrophoretic core-shell particles having an organic pigment core and a shell with a thin metal oxide layer and a silane layer

A method of manufacturing of an electrophoretic medium, the electrophoretic medium comprising a plurality of a first type of core-shell particles and a non-polar fluid, each of the plurality of the first type of the core-shell particles comprising a core comprising an organic pigment and a shell comprising a metal oxide layer and a silane layer, wherein the method comprises the steps of:

• providing organic pigment particles;
• introducing the organic pigment particles into a fluidized bed reactor as a powder bed;
• contacting the powder bed with a gaseous stream comprising an inert gas and a precursor of metal oxide;
• contacting the powder bed with a gaseous stream comprising a reagent that reacts with the metal oxide precursor to form a metal oxide, wherein the reagent is selected from the group consisting of water, oxygen, ozone, or mixtures thereof;
• reacting the organic pigment particles having a metal oxide layer with a silane compound in an organic solvent to form a silane layer, wherein the silane compound comprises a first functional group, a second functional group, and a third functional group, wherein the first functional group reacts with the metal oxide to form organic pigment particles comprising a metal oxide layer and a silane layer;
• combining the plurality of core-shell particles and the non-polar fluid.