以水平沈積法製備二元膠體晶體光學膜;Fabrication of binary colloidal crystal opal films by horizontal deposition method

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Title:	以水平沈積法製備二元膠體晶體光學膜;Fabrication of binary colloidal crystal opal films by horizontal deposition method
Authors:	王嘉偉;Wang,Chia-wei
Contributors:	化學工程與材料工程學系
Keywords:	無乳化劑乳化聚合法;水平沉積法;光子晶體;二元膠體晶體;Soap-free emulsion polymerization;horizontal deposition method;photonic crystal;binary colloidal crystal
Date:	2014-06-19
Issue Date:	2014-08-11 18:14:02 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文主要以無乳化劑乳化聚合法於常壓之沸騰環境下，快速合成均一粒徑次微米球與奈米球。並進一步設計其擁有不同特性，如具有不同粒徑次微米球、不同玻璃轉移溫度(Tg)次微米球以及不同官能基比例次微米球，以及不同玻璃轉移溫度的奈米球。依照其特性差異，成功地將其應用於提升光子晶體薄膜之機械性質。首先，利用不同甲基丙烯酸甲酯(MMA)單體克數製備出不同粒徑大小之次微米球，而MMA單體添加量4 g-10 g所製備之次微米球經自組裝過程後，其光子晶體能隙位置落於可見光範圍400-700 nm內。藉由Flory-Fox方程式調整丙烯酸丁酯(BA)與MMA單體之進料比可以製備具不同Tg之次微米球，當BA之重量百分比增加時，便可使次微米球之Tg由118.5 °C降低至-5.6 °C，且粒徑均相當均一。將具不同Tg次微米球於高低環境溫度下自組裝後，由結果顯示50 °C高溫環境溫度下有助於自組裝排列更為規則。Tg 40 °C以上之次微米球於SEM下呈現圓球狀並可顯現出結構性色彩。Tg 30 °C以下之次微米球於SEM下呈現平膜狀且不具備結構性色彩，但薄膜具有良好的成膜性質。薄膜的機械性質隨著次微米球的Tg降低，逐漸由脆性高分子轉變為彈性高分子。進而，藉由將低Tg奈米球與高Tg次微米球混合後，自組裝形成光子晶體薄膜。由SEM結果顯示低Tg奈米球於高溫環境下會軟化成殼，包覆於次微米球外圍形成殼層球，且具有規則性排列，造成光子能隙出現紅移現象。雖然光子能隙反射波峰強度降低，但是薄膜的成膜性質增加達到5B鉛筆硬度。藉由將高Tg奈米球與低Tg次微米球混合後，自組裝形成光子晶體薄膜。由SEM結果顯示，高Tg奈米球位於次微米球間的縫隙，形成光子晶體框架，防止低Tg次微米球於成膜過程中崩塌，進而使原本不具光子能隙的薄膜顯現出結構性色彩，並且具有高透明的性質。經拉伸測試後，薄膜的機械性質可由調整次微米球之Tg與高Tg奈米球之添加量而控制。最後改變低Tg次微米球之甲基丙烯酸(MAA)比例，隨著MAA比例增加，薄膜的機械性質逐漸由彈性轉變為脆性。藉由添加高Tg奈米球於薄膜中，經自組裝排列後可形成規則性結構，並顯現出結構性色彩。經拉伸測試後，由結果顯示薄膜的機械性質可由調整低Tg次微米球之MAA比例與高Tg奈米球之添加量而控制。 ;This study focuses on preparation of monodisperse submicron-scale and nano-sacle polymer spheres and the films forming ability by these two kinds polymer spheres. Submicrospheres with different particle sizes, glass transition temperatures (Tgs) and carboxyl groups were prepared. On the other hand, nanospheres with different Tgs were also prepared. The photonic crystal films with mechanical properties can be improved by self-assembly method of these two kinds of spheres. The five topics were discussed in this study. The first topic was preparation and characterization of monodisperse poly(methyl methacrylate-co-methacrylic acid) submicrospheres via soap-free emulsion polymerization. Different particle sizes from 82 nm to 502 nm were prepared by adding 1 g to 20 g monomers. In second topic, different Tgs submicrospheres were prepared by copolymerization of butyl acrylate (BA) and MMA. When the weight percentage of BA increased from 0 wt% to 88 wt%, the Tg of submicrospheres decreased from 118 °C to -5.6 °C. Photonic crystal films of these submicrospheres were then studied to identify the relationship between variation in Tgs and the optical properties. In third topic, the monodisperse low Tg nanospheres were prepared and mixed with submicrospheres to form self-assemble binary colloidal crystal (BCC) films. The results showed that submicrospheres surrounded by soft nanospheres and formed like core-shell structure with a regular arrangement. The film forming properties of hardness film prepared from high Tg submicrospheres improved to 5B pencil hardness by the aid of 20 wt% low Tg nanospheres. In fourth topic, the monodisperse high Tg nanospheres were prepared and mixed with submicrospheres to form self-assembly BCC films. The results showed that submicrospheres surrounded by hard nanospheres and formed a photonic crystal framework to prevent the collapse of the low Tg submicrospheres during film formation. According to the stress-strain diagram, the mechanical properties of BCC films were able to tune by the Tg of submicrospheres and the blended content of high Tg nanospheres. Base on the BCC film prepared by the Tg 0 °C submicrospheres and 20 wt% of high Tg nanospheres, the ultimate tensile strength and maximum elongation were able to achieve 0.78 MPa and 222 %. In fifth topic, submicrospheres with different carboxyl groups were prepared with MAA 0 wt% to 30 wt%. The results showed that the mechanical properties of the film changed gradually from elastic to brittle. When adding 20 wt% high Tg nanosphers into the film, the MAA ratio of submicrospheres changed from 0 wt% to 8 wt%, the ultimate tensile strength were able to increase from 1.3 MPa to 3.5 MPa and maximum elongation were able decrease from 359 % to 13 %.
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