堅固透明超疏水薄膜之製備與特性研究

Abstract

堅固透明超疏水薄膜之製備，不但須要使薄膜具備超疏水、自潔功能而且還須保持原有玻璃基板透明性，更需要具有抵擋衝擊堅固性。最重要的是，在節能與環保趨勢下，製造符合使用需求功能性薄膜的同時，從材料使用、製造過程以及最終產品，都要是對環境友善無害。超疏水性表面形成要素為「表面粗糙度」與「低表面能」，本論文研究探討超疏水性表面粗糙度構成，以15 nm與40 nm兩種粒徑之SiO2顆粒，搭配前驅物四乙氧基矽烷水解產物矽酸，於乙醇溶液中混合成溶膠凝膠溶液，以沉浸塗佈方式在玻璃基板製備粗糙表面，再以沉浸塗佈方式於粗糙表面披覆1H,1H,2H,2H全氟辛基三氯矽烷（1H,1H,2H,2H-perfluorooctyltrichloro silane, 8F）低表面能物質完成薄膜製備。經由SEM表面形貌觀察、穿透率與接觸角量測，並且以超音波聲震和滴水衝擊破壞，評估薄膜堅固度。驗證以15 nm SiO2顆粒與矽酸所構成之粗糙度，搭配1H,1H,2H,2H全氟辛基三氯矽烷製備之試樣D15B8F薄膜，呈現接近裸玻璃穿透率與超疏水性，機械與化學穩定性。 此外，以試樣D15B8F之粗糙度組成，搭配丙基三氯矽烷（Propyltrichloro silane, CH3(CH2)2SiCl3, C3）、辛基三氯矽烷（N-octyltrichloro silane, CH3(CH2)7SiCl3, C8）與十八烷基三氯矽烷（Octadecyltrichloro silane, CH3(CH2)17SiCl3, C18）等非含氟矽烷化合物作為低表面能物質，採用適合大尺寸基板塗佈之沉浸塗佈法與噴塗塗佈法兩種製程方式製備試樣。經由SEM與AFM表面形貌觀察，穿透率、接觸角、附著力量測、滴水衝擊與落砂撞擊破壞。評估以非含氟化合物C8在兩種製程方式下製備之薄膜具有可見光範圍77 %以上穿透率及超疏水性，耐滴水與落砂破壞堅固性，成功採用非含氟低表面能物質製備出環保、耐用、透明、超疏水薄膜。同時透過TEM觀察二氧化矽奈米顆粒與矽酸形成溶膠凝膠之微結構，為矽酸與二氧化矽產生緻密鍵結結合，聚集顆粒形成多孔性網狀結構；非含氟低表面能物質調配於乙醇溶液之反應特性，為自身聚合反應形成顆粒；採用ATR模式之FT-IR光譜偵測，解析薄膜表面組成不論是玻璃基板、矽酸、二氧化矽奈米顆粒與低表面能化合物各物質之間，皆是透過一對對矽醇官能基Si-OH鍵結結合成氫鍵，經由縮合脫水反應形成Si-O-Si共價鍵鍵結，提供薄膜堅固性來源，並且組成透明與超疏水性結構。 本論文研究經由超疏水表面組成要素，製備環保、耐用、透明、超疏水薄膜，探討薄膜表面結構特性、穿透率、超疏水性、堅固性及微結構與鍵結組成；採用沉浸塗佈與噴塗塗佈及80°C低溫烘烤方式，所開發製程可適用於大尺寸基板薄膜製備與減少能源消耗，具有工業化應用潛力。

Outdoor using self-cleaning glass not only has characteristics of transparency and superhydrophobicity but also needs durability and eco-friendly for environment. As well known, the property of superhydrophobicity composed of the roughness and the low surface energy material. For modifying roughness of superhydrophobicity, the coating thin film was dipped in a sol-gel solution containing 15 nm or 40 nm silica particles and silicic acid, in which the ratio of silica nanoparticles and silicic acid was varied to tune the roughness of the coating. Subsequently, the as-deposited coating was dipped with a low surface energy material, 1H,1H,2H,2H-perfluorooctyltrichloro silane. The coated glass substrate was characterized in terms of surface morphology, optical transmittance, water- and CH2I2-contact angles, and its chemical as well as mechanical stability was evaluated by ultrasonication. The properties of the coating hardly changed after the ultrasonication test and still retained the superhydrophobicity after water dripping. For eco-friendly issue, the thin film fabricated with nano-silica-particle/silicic acid sol-gel solution to build up rough structure onto glass substrate by dip or spray coating methods. Sequentially, the rough structure was covered low surface energy materials with non-fluorinated of Propyltrichloro silane, N-octyltrichloro silane (C8), Octadecyltrichloro silane via dip or spray coating processes. The dip coated thin film with compound C8 possess over 77% transmittance and superhydrophobic characteristic. The durability of the thin film was evaluated by water dripping, sand impact, and ultrasonication, the superhydrophobic characteristic properly remained. The sol-gel solution behavior and the low surface energy materials reactivity were investigated through TEM and FT-IR. The nano-silica-particle/silicic acid sol-gel solution was represented aggregation which formed a porous network structure. The silica particle was covered a dense structure by silicic acid cross-linking condensation. The FT-IR spectrums of the prepared samples show Si-O-Si bonding absorbing peaks. After analysis, the bonding reaction of the prepared samples process is confirmed by a pair of silanol functional group condensing to Si-O-Si covalent bond. Therefore, the bondings provided thin film robustness and constructed the transparent and superhydrophobic structure. This study prepared eco-friendly, robust, transparent, and superhydrophobic thin film not only discussing the surface properties but investigating the composition. Furthermore, the fabrication process is suitable for large-scale substrate production and performed under a low temperature baking. The advantages of saving energy consumption and industrialization have a potential extended to practical application.