The scattering mechanism of Mesoporous silica hollow sphere and the development of new type smart window

  • 黃 弘儒

Student thesis: Master's Thesis

Abstract

Over the past several years of research liquid crystals (LCs) the most fascinating field is that the anisotropic characteristic indicating the perpendicular direction of dielectric constant or refractive index is different from the direction of parallel Due to the intrinsic anisotropic characteristic the application of liquid crystal in the display field is attracting researchers and the display industry However the behavior of innate anisotropic fluid such as nanoparticles or colloidal particles is hard to well disperse in LCs As the restored elastic continuum of LCs and generated topological defects the doped nanoparticles couldn’t uniformly disperse in LCs and will gradually aggregate with the time or applied voltage However Mesoporous silica hollow sphere (MPSHS) is a candidate artificial material to solve particles aggregation in LCs and also make the controllable scattering effect for further application The subject of this thesis is to study the scattering phenomenon of MPSHSs and make a better performance of scattering devices such as smart window MPSHS-LCs exhibit uniform opaque in the naked eye and optical microscope images Contrary in the silica solid spheres (SSS) which without mesoporous on the surface of SSS and hollow structure the opaque is not uniformly distributed in the naked eye and optical microscope images In addition with the increasing applied electric field the dark section would be disappeared likely to the polymer dispersed liquid crystal Noticing the particular phenomenon we proposed the mechanism of light scattering and compare to the scattering phenomena of the polymer dispersed liquid crystals (PDLCs) and cholesteric liquid crystals (CLCs) According to the specific electro-optical behavior of MPSHSs we improve the performance of the smart window and we also propose the mixture of polymer (NOA61) and chiral (S811) to enhance the electro-optical property of MPSHSs Besides measuring the transmittance we also measure the response time and hysteresis effect which involve the anchoring of MPSHSs In order to find out more detailed about the light scattering mechanism and the orientation of liquid crystal surrounding to the MPSHSs so we use the azo dye (Methyl Red) which could induce the transient reorientation of liquid crystal by photoisomerization Based on the dynamics transmittance after the photoisomerzation of azo dye (Methyl Red) we could infer the reorientation of liquid crystal and the light scattering structure In addition we compare this phenomenon with PDLCs and CLCs Moreover the intensity of excitation laser energy is changed to observe the corresponding response about MPSHSs
Date of Award2015 Jul 27
Original languageEnglish
SupervisorKuang-Yao Lo (Supervisor)

Cite this

The scattering mechanism of Mesoporous silica hollow sphere and the development of new type smart window
弘儒, 黃. (Author). 2015 Jul 27

Student thesis: Master's Thesis