Preparation of titanium dioxide nanoparticles modified with methacrylate and their electrophoretic properties

Titanium dioxide nanoparticles (NPs) were modified by alkyl methacrylate (alkyl = methyl, butyl, ethylhexyl, lauryl and octadecyl) through graft copolymerization at its surface, respectively. The characteristics of these products were analysed by Fourier transform infrared, thermogravimetric analysis and transmission electron microscopy. The average particle size, zeta potential and electrophoretic mobility of modified NPs were tested in Isopar dispersion system and the water contact angle was also measured. The average particle size of NPs decreased; zeta potential, hydrophobicity and the dispersion stability enhanced with the increase of alkyl chain length. The maximum values of the zeta potential of NPs modified by poly(octadecyl methacrylate) (PSMA/TiO₂) electrophoretic particles reached −72.64 mV. The obtained NPs associated with carbon black were employed to prepare the display inks. An electrophoretic display prototype device based on the white–black inks was prepared. The results gave that the device based on NPs treated with poly(lauryl methacrylate) (PLMA/TiO₂) presented 357 ms of quick response under an applied 5 V (DC) field.