Preparation methods of alginate micro-hydrogel particles and evaluation of their electrophoresis behavior for possible electronic paper ink application

For the purpose of an electronic paper application, alginate/Ca hydrogel particles having a diameter of a few micrometers used with Titanium Black (TB), which has a diameter of similar to 1 mu m, for visualization purposes were prepared by mixing an aqueous sodium alginate solution with TB into an aqueous CaCl(2) solution. In order to increase their absolute zeta potential vertical bar zeta vertical bar for demonstrating good electric responsive behavior, micro-hydrogel particles were rinsed instantaneously by different concentrations of Na(2)CO(3) solution. Through this procedure, the absolute value of the zeta potential vertical bar zeta vertical bar in pure water increased from vertical bar zeta vertical bar=1.3mV for the minimum value to vertical bar zeta vertical bar=73mV for the maximum value with an upon increasing Na(2)CO(3) concentration. Micro-hydrogel particles were set between electrodes in pure water, their electro-responsive behavior was examined under an applied electric field and their position was analyzed using an optical microscopy. It was found that micro-hydrogel particles with a high absolute zeta potential vertical bar zeta vertical bar could oscillate from the anode to the cathode with a corresponding frequency, and threshold absolute zeta potential vertical bar zeta vertical bar was found to be between 1.3 and 39mV. Polymer Journal (2010) 42, 829-833; doi:10.1038/pj.2010.78; published online 1 September 2010