應用黏滯力及靜電力實現雙穩態粒子串電子紙

Abstract

本論文成功地利用溫控黏滯度與靜電力，展示一具有雙穩態特性的粒子極化反射式顯示介質。文中所提出的電子紙顯示技術有別於所有其他技術，係主要利用液體中粒子極化成串現象，進而改變顯示介質的穿透度達成明暗兩個顯示狀態。首先，我們利用了溫感型材料填加進入聚苯乙烯水溶液進行雙穩態特性之測試，在溶液黏滯度低時改變顆粒狀態，隨後以高黏滯度固定其中之顆粒。我們以4 wt%明膠-聚苯乙烯水溶液當成顯示介質，在室溫下連續測量一極化成串、明態之顯示介質，發現其穿透度於無外加電場與能量消耗下，在七個小時之觀察時間內並無明顯變化。除此之外，我們亦發現聚N-異丙基丙烯胺（Poly(N-isopropylacrylamide)）的添加可以改善粒子極化顯示介質的對比度表現。本論文亦利用矽油中正負相異電性之碳粉溶液 驗證靜電吸引力與粒子極化成串維持之關係。同時也測試以羧基及胺基修飾之聚苯乙烯，其表面攜帶相異正負電性之穩定效果，然而發現顆粒的帶電量過小，而無明顯維繫粒子串之現象。

We demonstrate a bistable reflective particle chain display medium by viscous and electrostatic forces. Different from other particle-based electronic paper technologies, the formation of the particle chains by an electric field changes the transmittance of the particle suspension and further determines the dark and bright states of the display medium. Here thermo-sensitive materials are dissolved into a polystyrene particle suspension. The particle chains are arranged at a proper temperature with a lower viscosity and stabilized at another temperature with a higher viscosity. By using 4 wt% gelatin, polystyrene, and water as the display medium, the particle chains can be maintained for at least 7 hr with no electric field applied. We also observe the contrast ratio of the display medium is enhanced by adding PNIPAM (Poly(N-isopropylacrylamide)). On the other hand, the electrostatic force is investigated for the stability of the polarized particle chains. The polarized particle chains containing printer toners with positive and negative charges dispersed in silicone oil are found more stable. We also test the particle suspension containing negative and positive polystyrenes particles whose surfaces are modified by carboxyl and amino functional groups, respectively. However, the polarized particle chains start to deform once the applied electric field is removed. We suspect that the electrostatic force is not sufficient for the inadequate charges of each particle.