The Preparation Of La₂O₃@AAO Nanocomposites And Their Electrowetting-on-dielectric Performance

The dissertation firstly gives a brief introduction of basic theories and models about wettability of solid material surface,summarizes the development history,present research situation and prospect of electrowetting-on-dielectric（EWOD）,and emphasizes the main challenges and problems to be further improved the performance of EWOD.Subsequently,according to the summarized EWOD models,the most important parameters to adjust the electrowetting-on-dielectric performance is dielectric constant of dielectric layer,so the La₂O₃ with high dielectric constant is selected as dielectric layer and study the influence of dielectric constant and surface nanostructure on the electrowetting（EW）properties,and it is also deposited into anodic aluminum oxide（AAO）to form composite to improve the EW properties of AAO.Thus,the dissertation uses“The preparation and EWOD performance research for La₂O₃@AAO”as thesis,mostly describes the following works and results:（1）Firstly,the electrowetting-on-dielectric test platform based on the static contact angle measuring instrument is established,it includes two parts of power supply and the contact angle measurement systems,and can test the EWOD performance and collect the related data.（2）Secondly,the EWOD of high dielectric material La₂O₃ has been studied.By the one-step solvothermal process,the urchin-like La₂O₃ structure has been fabricated.This method is simple,small energy consumption and environmentally friendly.It is more important that the morphology of the prepared urchin-like La₂O₃ can be tailored by changing reaction duration.The measurement of EWOD performance indicates that the initial contact angle without surface modification of low surface energy materials reaches to 118±4°,the contact angle modulation range can reach to 52°by only modulating the applied voltage from 0V to 20 V.Furthermore,the transition from the Cassie states to the Wenzel states also has been observed on the urchin-like La₂O₃ surface as the increase from 0V to 20 V of the applied voltage.（3）Thirdly,the as-prepared AAO by anodic oxidation was used as substrate,then was immersed into La（NO₃）₃ solution under ambient temperature and pressure and subsequent annealing to form the La₂O₃@AAO nanocomposites.The content of La₂O₃ in La₂O₃@AAO composites can be precisely modulated through the immersion time.It can be known that when the immersion temperature gets to 60 ^oC,the La₂O₃starts to grow in AAO by the characterization of morphology,crystal phase structure and surface chemical composition.The measurement of EWOD performance indicates that the incorporation of La₂O₃ into AAO greatly enhances the capacitance about 2-3 orders of magnitude,and the large contact angle modulation is acquired.Furthermore,the EW properties of La₂O₃@AAO nanocomposites,such as relaxation time,critical voltage,can be easily modulated by the immersion temperature and time.