电子墨水用SiO_2白色电泳颗粒的表面包裹及荷电

Surface Coating and Charge of SiO_2 White Electrophoretic Particles Used in E-ink

采用控制正硅酸乙酯在氨水-无水乙醇中水解的方法,制备出适合电子墨水使用的白色SiO2颗粒。将经H2O2浸泡,由甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)表面改性的SiO2颗粒,与苯乙烯单体分散在异丙醇中,采用自由基共聚法在SiO2颗粒表面包裹不同厚度的聚苯乙烯包4裹层。采用场发射扫描电镜(Field Emission Scanning Electron Micro-scopes)、高分辨率透射电镜(High Resolution Transmission Electron Microscopes)、傅立叶变换红外光谱(Fourier Transform Infrared Ray)、纳米粒度及Zeta电位分析(Zetasizer)等分析方法,研究了包裹前后SiO2颗粒的表面形貌、颗粒尺寸及包裹层厚,包裹后颗粒的表面化学键合情况,颗粒在四氯乙烯中的表面Zeta电位以及在四氯乙烯中的分散性。结果表明:自制SiO2颗粒呈球形,粒径约300 nm,SiO2颗粒表面包裹了聚苯乙烯,包裹层较为均匀完整,层厚约为10～25 nm,并随包裹颗粒时所加苯乙烯单体量增大而变厚,颗粒在四氯乙烯中的表面Zeta电位由-4.26 mV提高到-49.47 mV,包裹后颗粒在电势为9 V的电场下,响应时间理论计算值到达40 ms,颗粒在四氯乙烯中的分散性良好,分散后静置48 h,分散率可达到87%。

In order to prepare white electrophoretic particles, SiOz particles were prepared by hydrolysis of ethyl orthosilicate in ammonia/alcohol solution. The prepared SiO2 particles were immerged in aqueous hydrogen peroxide solution （30 % ,mass fraction）, and then surface was modified by 3-（trimethoxysilyl） propylmethacrylate （MPS）. The particles and styrene were dispersed in 2-propanol, then the SiOz particles were coated with different thickness by free radical copolymerization of styrene with MPS. The surface modality, size of the pure SiOz and coated particles, the surface chemical bond of coated particles, surface Zeta potential and dispersion in perchloroethylene were studied by scanning electron microscope （FESEM）, high resolution transmission electron microscopes , Fourier-transform infrared spectra （FTIR）, Zeta potential measurement. It is found that the polystyrene grafted on the surface of SiOz particles, coating layer was uniformity and full, the thickness of coating layer was about l0b 25 nm which thickened along with the increased quality of styrene, Zeta potential was improved from --4.26 mV to --45.73 mV, the response time of academic calculation achieved 183 ms, under electric field which voltage is 9 V, dispersion of coated particles was good, 48 h after dispersing, the best disperse rate reached to 87 %.