| 摘要: | 光子晶體，大多以PS (Polystyrene)、SiO2 (Silicon dioxide)等硬質球建造，展現了極差的成膜性、以及機械性質，大幅限制了可應用的範圍。因此，本實驗以克服上述缺點為主軸，在第一部分以硬核軟殼結構次微米球，建構光子晶體，以提升其成膜性。此外，進一步藉由混合兩種不同粒徑之高分子球的方式，製備一系列具有不同機械性質、由硬且脆到軟且韌特性的光子晶體薄膜。為了製備各種需求之高分子球，本論文亦發表了一種新穎、快速的合成方法，可在同一製程下，製備具各種不同粒徑、結構、特性之均一粒徑有機、或有機/無機高分子球。
首先，提出快速製備有機/有機核殼結構次微米球的方法。藉由PS球聚合的過程中，添加二階段單體BMA (Butyl methacrylate)的方式，可於2 小時內快速製備PS/PBMA核殼結構次微米球。進一步將其進行光子晶體的自組裝，並藉由鉛筆硬度計測試機械性質。實驗結果指出，藉由組裝硬核軟殼次微米球的方式，可將光子晶體之機械性質，由原本的低於6B，提升至HB。
然而，藉由硬核軟殼結構次微米球組裝之光子晶體，屬硬質膜。因此，製備一系列玻璃轉移溫度(Tg)介於-34 ℃至112 ℃之次微米球。並將其與PS奈米小球混合(≒20 nm)，藉此建構一系列具有不同機械性質之光子晶體。SEM結果指出，次微米球以六方最密堆積的方式排列，PS奈米小球則位於球與球的間隙中，防止次微米球於光子晶體建構過程中坍塌。由應力、應變圖的結果顯示，光子晶體之機械性質，可由兩種可行的方式控制，使之由典型的彈性體慢慢變化為脆性高分子。其一為提升次微米球的Tg從-34 ℃至8 ℃
而第二種方法則是在Tg為-34℃之光子晶體內，增加PS奈米小球之混合比例從5 wt. %至25 wt. %。基於以上兩種方法，光子晶體之極限抗拉強度與最大形變量，可以分別達到4.7 Mpa與1236 %。
當光子晶體展現出彈性體行為時，特別具有應用價值，因其光學特性與光子晶體的應變有相對關係，即具有機械應答的能力。因此，在一系列具有不同機械性質之光子晶體中，選擇PBA次微米球，進行更深入的探討。實驗結果指出，隨著PBA次微米球粒徑的增加、或是PS奈米小球於光子晶體中混合量的提升，皆會造成光子晶體之光子能隙有紅移的現象。而當光子晶體受到應力拉伸時，光子能隙表現出了藍移的現象，且λmax的行為符合Poisson 效應。
有別於之前所建立的快速合成有機高分子球的技術，進一步的，藉由選擇二階段單體為矽烷混合物，將此技術延伸至可製備有機/無機PS/SiO2核殼結構次微米球。矽烷混合物之極性，以及其建立之SiO2的機械強度，可藉由改變MTES (Triethoxymethylsilane)與TEOS(Tetraethyl orthosilicate)間之混合比例而調整。且僅藉由簡單的擴散作用力，就可擴散進入PS球之外圍，反應成為SiO2。最後，將PS/SiO2次微米球，進行高溫鍛燒，可得中空SiO2球。
In general, the tranditional colloid opals were constructed mostly by hard spheres, such as PS (Polystyrene), SiO2 (Silicon dioxide) and so on. These opals exhibited awful mechemical and film properties, thus limited the application fields. For these reasons, the main purpose of this thesis was based on the conceptions to overcome above-mentioned disadvantages. At first, the promoted film properties of opal were carried out by constructing from hard core-soft shell structure spheres instead of typic hard spheres. Secondly, the opals with a series of mechanical properties between rigid-brittle and soft-tough polymer behaviors were further prepared by blending two different diameter spheres. In order to synthesize various, required spheres, a rapid, novel synthesis technique was also presented herein. Base on this technique, the monodispersed organic or organic/inorganic spheres with various diameters, structure and properties were able to synthesize in the same procedure.
In the first chapter, the technique for rapid synthesis (2 h) of organic/organic core-shell structure spheres was presented. Monodispersed PS core was polymerized for a period of time, and then BMA (Butyl methacrylate) monomer was introduced to the reaction system to prepare the core-shell PS/PBMA spheres. Subsequently, these core-shell spheres were self-assembled into opal, and examed by pencil hardness test. The results indicated that the mechanical properties of opals were able to promote from original lower than 6B to HB as the core-shell shperes were applied.
However, the category of above opal is hard film. Therefore, a series of submicrospheres with different Tg between -34 ℃ and 112 ℃ were prepared, and further blended with nano PS apheres (≒20 nm) to construct opals. The SEM results indicated that the soft submicrospheres were hexagonally arranged, and the nano PS apheres occupied the interstices, to keep the periodical structure. According to the stress-strain diagram, the mechanical properties of opals were able to tune by two main ways to make the film behavior changed from typical elastomers to brittle plastic. One of wich was increasing of submicrospheres Tg from -34 ℃ to 8 ℃
And second way was to increase the blended content of nano PS apheres from 5 wt. % to 25 wt. % in the presence of -34 Tg submicrospheres in opal. Base on the above approaches, the ultimate tensile strength and maximum elongation of opals were able to achieve 4.7 Mpa and 1236 %, respectively.
The opal with elastic polymer behaviors possessed great application values because of which exhibited the relationship between the film elongation and optical properties, called mechanical respounsed ability. Thus, the PBA elastic opal was choosen to further study. The results indicated that the red-shifted photonic band gap of elastic film was able to controll by the increased diameter of PBA spheres, or small PS content in opal. On the other hand, the bule-shefted photonic band gap was observed as the elastic film was stretched. And the shifted behavior of λmax was corresponded to the Poisson effect.
Different from the previous technique of rapid synthesis of organic/organic spheres, mixed silane was choosed as introduced monomer to extend the technique to synthesize organic/inorganic PS/SiO2 spheres. The polarity of mixed silane and the mechanical properties of fabricating SiO2 were able to tune by adjusting the feeding ratio between MTES (Triethoxymethylsilane) and TEOS (Tetraethyl orthosilicate). Subsequently, the silane was introduced onto the surface of PS particle, just by acting force of simple diffusion, and further reacted to SiO2. Finally, the monodispersed, hollow SiO2 spheres were obtained by calcinating the PS/SiO2 spheres. |
