Contributions of Different Functional Groups to Particles in Electrophoretic Display

Electrophoretic display (EPD) has excellent research potential because of its ultra-low power consumption and friendliness to the eyes. To obtain efficient electrophoretic inks, researchers need to understand the charging mechanism of electrophoretic particles. In this work, several silane coupling agents with similar main chains but different functional groups on the side chains were used to investigate the effects of different functional groups on the charging properties of the electrophoresis particles. The results showed that silane coupling agents containing amino groups resulted in the most positively charged particles, and those containing carboxyl groups resulted in the most negatively charged particles. More importantly, after introducing many additional amino groups by grafting, it was found that the charge on the particle surface was only slightly elevated, indicating that the polymer layer grafted on the particle surface would cover the functional groups inside and hinder the acid-base interactions between the functional groups in the inner layer and the charge control agent. The findings of these results may contribute to the precise design of materials for electrophoretic display.