电子墨水用白色电泳颗粒的制备及其表面改性

为制备出适用于电子墨水的白色电泳颗粒,采用控制正硅酸乙酯在氨水-乙醇溶液中的水解来合成S iO2颗粒。为提高S iO2颗粒于四氯乙烯溶液中的电泳性能,取1 g合成的S iO2颗粒,于30℃经w(H2O2)=30%的双氧水浸泡12 h后,与3 g丁二酸在100 mL乙腈介质中,于75℃进行回流加热反应24 h,将丁二酸化学键合于S iO2颗粒表面。最后,为降低电泳颗粒密度,将0.2 g经丁二酸改性的S iO2颗粒,于90℃时加入已溶解了0.1 g聚乙烯(PE)的50 mL二甲苯中,冷却静置12 h后,以10 000 r/m in的速度离心,使PE沉积包覆于电泳颗粒表面。傅里叶红外光谱(FTIR)图表明,丁二酸一端的羧酸基团与S iO2颗粒表面的羟基发生了酯化反应。透射电镜(TEM)证明,经丁二酸改性的S iO2颗粒被PE包覆,且包覆后的形貌为球状,粒径在300 nm左右。Zeta电位测试结果显示,经表面改性后,S iO2颗粒在四氯乙烯溶剂中的Zeta电位由-4.261 mV提高到了-27.84 mV,提高了5.53倍。

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.