Fast Response and Enhanced Light Fastness of Yellow Electrophoretic Particles with Copolymer Shell Layer

Electrophoretic display (EPD), a reflective display technology, has demonstrated considerable potential in the information display field owing to its advantages of low power consumption, wide viewing angles, eye protection, and high readability under intense light. With the maturation and commercialization of black-and-white EPDs technology, achieving color EPDs has become a central focus in the advancement of this discipline. To address the associated challenges, this paper proposes a copolymer shell encapsulation strategy. By grafting a silane coupling agent onto the surface of a yellow organic pigment and subsequently constructing a poly(styrene-co-methacrylic acid) copolymer shell, the core-shell structured yellow electrophoretic particles are eventually prepared. With carboxyl polar groups incorporated into the shell layer, the Zeta potential reaches -92.9 mV, which enables a fast electrophoretic response of less than 100 ms under a driving voltage of 20 V. The copolymer shell acts as a physical barrier that enhances light fastness, leading to a smaller decrease in visible absorbance under natural sunlight exposure for the encapsulated particles than for the pristine pigment. Furthermore, the particles are prepared using anhydrous ethanol as the solvent and dispersed in Isopar G to formulate the yellow electrophoretic dispersion, aligning with green chemistry principles. This work suggests that the proposed copolymer shell encapsulation strategy effectively enhances both the surface charge density and light fastness of yellow electrophoretic particles, highlighting its promising potential for application in fast-response, high-stability color EPDs.