Dual-silane coupling agents co-grafted on black particles for fast response and high contrast ratio electrophoretic display

Abstract

As the Internet of Things (IoT) significantly improves people's lifestyles, flexible and low-power displays will become essential to real-time human-computer interaction. Electrophoretic display (EPD) has many advantages, such as low power consumption, flexibility, and high sunlight visibility, which is necessary for IoT terminal display. However, preparing electrophoretic particles with high charge and spatial resistance is difficult. Herein, dual-silane coupling agents, (3-Aminopropyl) trimethoxysilane (APS) and vinyltrimethoxysilane (VTS), were co-grafted on the black particles to optimize the electrophoretic particles' dispersity and charge. To evaluate the charge content and dispersity of particles, we measured the particles with zeta potential, dynamic light scattering, and long-term standing treatment. Fe3O4-APS0.5VTS0.5-PLMA, selected as the black particles for EPD, had an average particle size and zeta potential of 300 nm and 25 mV, respectively. Besides, the concentration of the black and white particle would significantly affect the EPD's performance. When optimizing the white and black particle concentration to 4:1, the contrast ratio of EPD was up to 13.2. In addition, the EPD has a response time of 200 ms and exhibits an invertible black and white state under ±15 V. Finally, to improve the stability of electrophoretic particles, the particles were encapsulated in microcups and driven to the black and white state under 30 V. This work demonstrated that dual-silane coupling agent particles have the potential to achieve the fast response and high contrast ratio EPD.