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  • 學位論文

環烯烴共聚物分子結構對其混摻及奈米複合物薄膜之型態與光學物性影響研究

Morphologies and Physical Properties of the Cyclo-olefin Copolymer Blends with Different Molecular Structure and their Nanosilica-modified Composite Films.

指導教授 : 李育德
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摘要


以金烯觸媒聚合之乙烯-環烯烴共聚物(Metallocene Catalyzed Ethylene Cycloolefin Copolymer, mCOC),具有硬挺之環狀結構單體、隨機排列之共聚合分子鏈段、完全飽和之碳氫鍵結及沒有殘存雙鍵或會吸水的官能基,可產生耐熱而完全透明之非晶相高分子,且不易受溫溼度影響而引起產品尺寸變異,環境安定性優良,這是許多光電產品迫切需要的特性。但光電材料除要求透明度外,還須達到特定折射率、色散值、雙折射性,同時還要依據產品形態如薄膜或複雜形狀,配合適當的加工製程如溶液塗佈、押出或射出成形等。化學合成與混摻改質都是常用的改質手段,但是對非極性的聚環烯烴材料而言,,以極性化改質會喪失其原有優勢,並不是好的選擇,利用分子微結構不同產生的各種微小分子斥力之間的平衡,或可找出另一調控光學高分子特性的新途徑。 本研究利用溶劑共混或雙螺桿熱混摻製程,製備COC薄膜。薄膜特性受金烯觸媒種類、冰片烯含量和共聚物的微觀結構呈現不同的相容性與光學性質。而熱押出加工可使不相容混摻膜得到不明顯的相分離與更低霧度。相同觸媒COC共混時,若冰片烯含量差距大於15.5mol%,高分子會不相容。而使用不同觸媒的COC混摻時,相容區域縮小至11mol%,故高分子微結構的不同會影響相容性。 以溶劑成膜不相容高分子會因相分離而使得膜呈現混濁;而使用雙螺桿擠出熱加工,可以降低高分子微相尺度可小於100nm,再加上折射率相近,故此方法混摻後的膜會呈現透明(Haze < 2 %)。 5013硬脆性質可仿橡膠韌化理論加入高韌性8007混摻,提升薄膜韌性。低雙折射率的5013與6013混摻成膜,可降低6013的雙折射率,又不會降低Tg與耐熱性。以5013為連續相之混摻薄膜,可得到更低的雙折射,更適用於如相位差補償膜、偏光保護膜等。 同時本研究希望利用低極性奈米粒子與mCOC間微觀分子斥力,抑制其相分離現象,進而維持其高穿透度之特質。同時利用疏水化奈米粒子Hb-SiO2添加于COC材料中,由SEM與TEM等形態學觀察可知,其分散效果遠優於親水性奈米粒子Hp-SiO2。同時機械物性與光穿透性也較佳。Hb-SiO2其表面C8碳鏈改質,加入 COC混摻物可緩衝拉伸使拉伸模數下降。反之,Hp-SiO2雖為C4改質,但數量不足以屏蔽OH基使表面仍呈親水性,故無法產生分散與緩衝效果。 Hb-SiO2加入不相容 COC混摻物可抑制相分離與減小兩相domain尺寸,進而降低光學霧度,提升光穿透特性。本研究之COC混摻物與添加奈米粒子後之複合膜,其穿透度都接近商品薄膜程度。如能進一步微調COC與奈米粒子表面改質的分子微結構,將有機會進一步提升其光學應用之機會。

並列摘要


Metallocene catalyzed cycloolefin copolymers (mCOC) are transparent, rigid, high Tg and low water uptake because of the saturated hydrocarbon nature, the rigid cyclic norbornene comonomer and the randomly arranged copolymer chain, which properties are urgly needed by the optoelectronic industry. But other properties such as pecific refractive index, dispersion and birefringence are also needed. In the mean time, the rheological properties should be tuned to the processing method to make the optical product. Besides of the chemical synthesis, physical blending is an economic way to modifiy the existed polymer. Because of the advantages of mCOCs’ low polarity and dimensional stability, modification by polar functional groups is not a good choice. To utilize ven der Waal repulsion force from the small difference of the copolymer molecular microstructure, it might be a new way to manipulate the phase domain as well as the properties of the non-polar polymer blend and their inorganic particle filled nanocomposites. A series of Cyclo-olefin copolymer (COC) blends were prepared via solution blending process and showed various miscibility because of different norbornene content as well as copolymer microstructure. Two kinds of nano-silica particles, including hydrophilic silica (Hp-SiO2) and hydrophobic silica (Hb-SiO2) were inducted into COC blends to deform the phase separation domains of COC blends. The properties and morphologies of the composites were characterized after preparation. The tensile moduli of 8007 blended films increase with increasing 5013 or 6013 content. The tensile moduli of the COCs composites slightly decrease either with 1wt% Hp- or Hb-SiO2. But the tensile strength and elongation increase as the 6013 content higher than 30wt% in the 8007/6013 composites with 1wt% Hb-SiO2 particles. By adding either Hp- or Hb-SiO2 particles, the haze value decreased in the immiscible blends (8007/5013) but slightly increase in the miscible blends (8007/6013). For all COCs and their blends, the transmittances are all higher than 85% with 1wt% Hb-SiO2 loading. The phase separated domains deformed with nanosilica in 8007/5013 composites which might be a reason for lower haze. In addition, transparent composite materials can be manufactured from immiscible COC blends containing nanoparticles.

參考文獻


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