Preparation and Surface Modification of White Electrophoretic Particles Used in E-ink

In order to prepare white electrophoretic particles,SiO_2 particles were prepared by hydrolysis of ethyl orthosilicate in ammonia/alcohol solution.Surface modification is done to improve electrophoretic capability of the SiO_2 particles in tetrachloroethylene.1 g of the prepared SiO_2 particles were immerged in aqueous hydrogen peroxide solution(w(H_2O_2)=30%) for 12 h at 30 ℃,and then esterified with 3 g succinic acid in 100 mL acetonitrile for 24 h at 75 ℃.At last,in order to lighten the electrophoretic particles,0.2 g of the succinic acid modified SiO_2 particles were dispersed at 90 ℃ in 50 mL xylene solution dissolving 0.1 g polyethene(PE),cooled and kept for 12 h,and then the particles were encapsuled by PE by means of centrifugal sedimentation at(10 000) r/min.FTIR shows that one end of succinic acid was chemically bonded to the SiO_2 particle through esterification.TEM shows that the morphology of modified SiO_2 particles is spherical in size about 300 nm and encapsuled by PE.Zeta potential of the modified SiO_2 particles in tetrachloroethylene solution is improved from-4.261 mV to-27.84 mV.