Studies On The Modification Of Black Nanoparticles For Electrophoretic Displays With Environment-friendly Medium

Electrophoretic displays,profiting from their merits of wide viewing angles,light-weight,reliability and low power cost,are popular in reflective display fields.Furthermore,electrophoretic displays can act as substitute for paper to reduce the deforestation.To date,black-white electronic books based on microencapsulated electrophoretic displays have been commercialized,however,the display performance including contrast ratio,response time and bistability of electrophoretic display still needs to be improved.This contribution devoted to the surface modification of black particles to improve the performance of electrophoretic display.To enhance the display property of electrophoretic display,polyacrylic ester were employed to modify carbon black particles to improve their dipersity in Isopar L.Non-ionic surfactants were selected to treat carbon black and copper chromite black particles to investigate their charging behavior.polyacrylic ester were used to proceed the grafting modification of carbon black particles by a redox polymerization method.Results showed that aggregation of modified carbon black particles reduced distinctly and their particle charge enhanced.Particularly,compared with other particles,carbon black particles grafted with poly?ethylhexyl methacrylate?were endowed with the largest particle charge of 36.50 mV and excellent dispersity.The display prototype based on ethylhexyl methacrylate modified carbon black particles displayed the highest contrast ratio of 11.13 and minimum response time?527 ms?compared with the ones prepared with other particles.Carbon balck particles were modified by polyisobutylene-mono-succinimide?T151?.Particles charge of modified carbon black particles increased with the increase of T151 concentrations and presented a remarkably high electrophoretic mobility of-11.56×10-10 m2/Vs and a zeta potential of-180.3 mV at the T151 concentration of 2.0 wt.%,which are the highest values for CB in nonpolar media reported by far.The dispersion stability of carbon black suspensions was dramatically improved with T151,which is evidenced by the lower transmittance of 18%,reduced particle size from 1103.5 nm?raw carbon black partilces?to125±10 nm?modified carbon black particles?and no particle migration behavior occurring between Isopar L and deionized water.Moreover,transmittance and particle size showed nearly no change for 30 days.Prototype electrophoretic display device based on 2.0 wt.% T151 treated carbon black particles exhibited highly improved performance?preferable contrast ratio?6.6?,shorter response time?513 ms?and improved biastability?compared to that of device using pristine CB particles.Copper chromite black coated with silica?copper chromite black/SiO₂?were successfully endowed with negative particle charge in nonpolar Isopar L with the presence of nonionic surfactants?Span80,Span85 and T151?.The samples possess a maximum particle charge of-12.95 × 10-10,-14.18 × 10-10 and-17.43 × 10-10 m2/Vs at 12,16,16 mM for Span80,Span85 and T151,respectively.Moreover,electrophoretic fluids containing T151 display excellent insulativity evidenced by their low leakage current.Significantly,prototype electrophoretic display employing T151 treated copper chromite black/SiO₂ particles exhibited a quite quick response?response time: 189.6 ms?with white-black contrast ratio of 6.27 under 0.3 V/?m.The electrophoretic microcapsules using Isopar L which is environment friendly as dispersion medium were prepared in this article.Results demonstrated that when the ratio of core material to capsule material is 4:1,the microcapsule wall is cured at pH=8.5,disperse time and rate was 20 min and 800 rpm,respectively,microcapsules with smooth surface,narrow size distribution ranged in 30⁶0 ?m and high yield of 83.9% were obtained.Bu applying in electrophoretic display,the device displayed in the form of clock display and active display.