- 學位論文
聚丙烯膜材表面超疏水化電漿改質技術及形成機制之研究
Investigations on Plasma Modification Processes and the Mechanism in Forming Super-hydrophobic Surfaces on Polypropylene Membranes
摘要
本研究以聚丙烯（Polypropylene）為基材，利用CF4電漿進行表面改質，探討電漿功率、改質時間、氣體流率、改質面積、膜材結晶度與SF6電漿改質對膜材表面疏水及疏油性質的影響。並利用WCA、SEM、AFM、XPS等儀器分析表面物理形態與化學組成之變化，搭配電漿放射光譜儀（OES）分析電漿中物種濃度的變化。 首先使用CF4電漿對PP膜材進行表面改質，發現改質後膜面具有超疏水（~160°）及疏油（~120°）特性，接觸角遲滯現象與滑落角可低於10°。電漿改質後膜面氟碳比約為1.3，顯示改質後膜面具有PTFE-like的化學結構外，膜材表面形態亦有明顯變化，使表面具有超疏水的特性。由SEM及AFM發現膜面具有兩種尺度的微結構粗糙度，由於PP膜材本身具有結晶度，電漿改質下結晶/非晶區蝕刻速率不同，將會造成主要的山脈狀次微米級結構粗糙度；第二層奈米級的粗糙度則是被蝕刻出的產物部分沉積回表面形成顆粒狀結構。 研究中發現降低氣體流率及增加電漿功率都能提升表面粗糙度：降低流率會產生電漿聚合效應，表面在覆蓋一層氟碳膜後電漿主要為蝕刻效應，造成表面粗糙度提升；增加功率則會加強離子轟擊的效果，粗糙度也隨之提升。因此在相同改質時間下，可利用電漿參數的調整達到所需之粗糙度。 將進料氣體由CF4改為SF6進行改質，發現PP膜材無法達到超疏水的特性，並從SEM圖中發現表面並沒有明顯的粗糙結構產生，說明SF6電漿是以氟化效應為主，電漿中產生大量的氟自由基和表面碳懸鍵形成鍵結，沒有像CF4電漿一樣具有氟碳沉積效應加速結晶/非晶區蝕刻速率，因此表面無法形成粗糙結構。但在降低氣體流率時，表面發現到些微的粗糙結構，疏水性也有明顯的提升。 使用非晶性的PP同樣進行CF4電漿改質，發現表面形態完全不同於半結晶性的PP膜材，原本的山脈狀微結構轉變成碎形微結構，此種結構將使得表面具有超疏水、超疏油的雙重超疏特性，更有助於減少表面的運動障礙，使得接觸角遲滯現象及滑落角大幅降低。 電漿放射光譜分析結果顯示，將電漿中氟（F）與氫（H）的特徵峰相除作比較，會有一明顯變化趨勢，此趨勢與XPS分析中的氟碳比變化類似。另外在通入不同氣體流率時的光譜也有不同變化趨勢，與膜材表面物理型態與化學結構的分析作連結，利用光譜即時性的監控分析，了解改質過程中膜材表面的變化情形。
並列摘要
Super-hydrophobic and oleophobic surfaces were produced on polypropylene（PP）membrane by CF4 plasma treatment in this study. The PP surface’s water contact angle was greater than 160° and methylene iodide (CH2I2) contact angle was greater than 120° after plasma modification. Further, the water contact angle hysteresis (WCAH) and the sliding angle were less than 10°. It reveals that plasma-treated surface had excellent water-repellent, oil-repellent and self-cleaning characteristics. The results also revealed that the membrane’s surface roughness was significantly increased and surface fluorination occurred rapidly by the plasma treatment. The plasma-treated PP surface was found to consist of two-tier surface roughness. The ridges and valleys structures created by the etch rate difference between amorphous and crystalline region of isotactic polypropylene （i-PP）presented the first tier roughness. The nanostructures seen on both ridges and valleys presented the second tier roughness. This could be attributed to the redeposition of etch products, as evidenced by the weight increase of plasma-treated samples in the initial stage. CF4 plasma treatment was also conducted on amorphous atactic polypropylene (a-PP) coatings. The surface morphology of plasma-treated a-PP was quite different from crystalline i-PP. The ridges and valleys structures transferred to fractal-like structures. This structure could contribute the air-cushion which promoted significant water-repellency and oil-repellency (CA＞150°). WCAH and sliding angle of plasma-treated a-PP were very low when compared with i-PP results, indicating that plasma-treated a-PP exhibits perfect self-cleaning characteristic.