別紙4 (課程博士)
Date of submission

平成28年

7松田厚範教授

武藤浩行教授月15日

Department
S加dentlD Number

電気・電子情報 工学

学籍番号

専攻
Pplica11t's nalne

氏名弟 115406 号
Supervisors

指導教員

Weixin宮Abstract

論文内容の要旨(博士)T北le ofThesis

Wettability/surface potentialcontr010n different interfaces and their applications

博士学位論文名

On optical and electrochemical devices(異種界面における濡れ性と表面エネルギーの制御と光学および電気化学素子への応用)(Approx.80o words)(要旨 1,200字程度)
Being a11 attractive topic, surface wettability/potential has been we11 Studied in the last twodecades. contr011ing ofthe wettability and surface potential has ma11y areas ofapplications such as
bio・fouling,1iquid lens fabrication a11d the electrophoretic deposition (EPD). contr011ability ofthe
S11rface wettability/potential by physical al)d chemical methods has been studied in tMs work. By
analyzing 釘ld using different principles, the application of surface wettabilityゆotential contr01
Were expanded to make optical a11d electrical devices with higher performances.
In the first study, the wettability ofNafion f11m was foU11d to have a time dependent: contactangle (CA) of a water droplet on the Naflon film reduced from 149゜ t0 134゜ within one minute'゛毛气The change in cA could be explained from the molecular stNcture ofNafion, which is a polymer
material containing long branches with suHonic group endings.圦7hen the interface cha11ged fromair介、1aflon into watern、Jafion, according to the surface potential, these bra11Ches becalne upright or
bend over. This causes a "aゆ・aop" wettability change phenomenon. To study the e貸'ect of theapplied voltage on this phenomenon, we used multilayered thin films of 67111n Naaon / 1501)1n
Ti02 / 110 r11n pt coated on silicon wafer. The results showed that when a water droplet was loaded
by positive Dc voltage higherthan 2V, owing to the strong attraction force towardsthe sulf011ic topgroups,the unwinding ofthe bra11Ched chains in the polymerf11m becomes enha11Ced. Adecrease inCA to a minimuln of 20゜ ca11 be obtained in two minutes. conversely, a negative Dc voltage
inhibitsthe "aip・aop" property by giving repulsive force towardsthe sulfonic groups.
In the second study, electrowetting propeny on dielectric multilayered thin 丘lms wasinvestigated. similar to "aゆ・aop" wetting, electrowetting is a modificationof the wetting
Propedies on a solid surface by using an appHed voltage.1eaon was used as the hydrophobic top
Iayer in this study, owing to its remarkable cA reversibiliw. Multilayered tMn films of 50 111n
Ieaon / 1601血 Ti02 / 801血 A1203 / on lTo glass were used as the solid phase. The Ti02 1ayer
Was added to increase dielectric constantfor a larger cA changing range. Mea11While, the A1203Iayer was used to give high dielectric strength to prevent breakdown. S01・gel and chemicalsolution
dip coating processes were used to prepare each layer. By measuring the cAs with ditferent appliedVoltages, we foU11d that negative Dc is more stable tha11 Positive DC.1n addition, by testing theIeakaσe cunent during the electrowetting, the most suitable working voltage was obtained to be to・10 V DC.1n dodecal)e atmosphere, the cA of a water droplet on leaon surface was contr0Ⅱed
丘om 155゜ t0 67゜ by loading with ・10 V Dc without a11y electric breakdown. Funhermore, when
the same multilayers were coated on the inside of a glass tube, the curvature of the water・oil
interface could be adjusted by the applied voltage a11d due to the ditferent refiactive indices ofWater a11d oil, Hght passing thoughtthe interface can be converged or diverged depending on theCurvature. By this principle we designed a11d assembled a liquid focusing lens driven byelectrowetting.1he perfomla11Ce of the liquid lens was tested based on its ral)ge of focusing
Iengths, response time, and life time. The results showed that by increasing the voltage from o v tof︑・10 V, the foca11ength changed from ・2 mm to infinity then to +10 mm. The lens had a quick
response time ofless than loo ms al)d it was sti11Stable after 180010ading periods.
In the finalstudy, on dye・sensitized solar ce11S (DSSCS), we prepared silver nanoparticles (AgNPS) with high zeta・potentiala11d improved a method ofmaking Ag NPS/ 1i02 nal)otubes (TNIS)
Composite, by electrophoretic deposition (EPD). Ag Nps with an average size of 25 1)1n weremodified by carboxy methylceⅡUlose on their surfacesto obtain a Mgh zeta・potentialof・433 mv.
INlanays with a thick)ess of 13 μm were groW11by al)odizing lifoils. EPD was employed to fi11
the TNT arrays with Ag NPS. A combination of +2 V Dc and square waved 4 V Ac with afrequency of l Hz proved to be the most e丘ective appHed voltage for EPD according to the results
Obtained by quantitative analysis of deposited Ag NPS. AISO, an acetone vapor pretreatment wasinvented to replace the air in the TNTs before the EPD process. Back i11Uminated Dsscs werefabricated with the TNlanays with di丘erent EPD time. Afterthe TNT arrays waS 負11ed by AgNPS
Using 30 min EPD time,the e缶Ciency ofDsscsincreased from 3.70% t05.01% dueto the surface
Plasmon resonance e丘'ect. However, the e錨Ciency decreased t0 4.62% witl) excess Ag NPS
deposition when the EPD time wasincreased t060 min

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