Nano titanium dioxide particles modified with poly(lauryl methacrylate) and its electrorheological and electrophoretic behavior

• A novel ER fluid is prepared by PLMA/TiO2 dispersed in low-viscosity isoparaffin.
• PLMA/TiO2 ER fluid shows perfect electrorheological behavior under electric field.
• PLMA/TiO2 ER fluid is successfully used for electrophoretic displays.
• The maximum contrast ratio of a micro-cup device is 6.2 and response time is 288 ms.

In this paper, we reported a new non-aqueous electrorheological (ER) fluid structured by TiO2 nano-particle modified poly(lauryl methacrylate) (PLMA/TiO2) dispersed in low viscosity isoparaffin and studied its electrorheological behaviors. Moreover, the ER fluid was applied to electrophoretic display at the first time. PLMA/TiO2 particles were prepared via graft copolymerization using γ-methacryloxypropyltrimethoxysilane and lauryl methacrylate, successively. The thickness of the cladding layer of nano titanium dioxide surface was about 2.9 nm. When an external electric field was applied to this dispersed system, from 0 to 4.5 kV/mm, the ER fluid showed a good rheological property and the viscosity of ER fluid was increased from 20 to 160 mPa s. The shear stress strengthened with PLMA/TiO2 particles weight fraction increase in dispersed system. As a white medium, the ER fluid was mixed with carbon black to prepare a micro-cup electrophoretic display device, which could successfully realize electrophoretic display for white and black state under an electric field. The maximum contrast ratio of the micro-cup device was 6.2, and response time was 288 ms, and the clock micro-cup device could maintain display state than 24 h in the absence of electric fields.

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