- 學位論文
探討聚苯醚碸基材膜表面型態對電漿聚合層物理結構之影響
Investigation on the effect of PES membrane surface morphology on the physical structure of plasma-polymerized film
摘要
本研究目的在探討不同基材表面型態對電漿聚合層結構之影響，實驗以濕式相轉換法，藉由調整成膜路徑，製備出具有三種不同表面型態(緻密皮層、多孔皮層及無皮層)之聚苯醚碸(Poly(ether sulfone), PES)基材膜。並以高週波電漿輔助化學氣相沈積反應系統(Radio Frequency-Plasma Enhanced Chemical Vapor Deposition, RF-PECVD)，進行乙炔氣體電漿聚合反應，沈積具有高均勻性及良好基板附著性之電漿披覆層，以製備出具高透過量之非對稱膜材。同時利用掃描式電子顯微鏡(Scanning Electron Microscopy, SEM)觀測薄膜經電漿聚合之結構型態變化，並結合正子湮滅光譜(Positron Annihilation Spectroscopy, PAS)量測技術，探討電漿複合膜不同層間奈米結構之變化，釐清基材膜表面型態對電漿聚合層物理結構之影響。 由水蒸氣透過測試結果可發現，在相似厚度之聚合層條件下，不同表面型態之基材膜會影響電漿複合膜的透過性質。當基材膜表面為蕾絲狀無皮層結構(T3)時，可製得具低透過阻力之電漿沈積層。在電漿參數(電漿功率、沈積時間、乙炔進料流量及氬氣添加)對不同表面型態基材膜之電漿聚合層結構型態影響之探討中，具不同表面型態之基材膜，經相同電漿聚合反應後，可製得具相似厚度之聚合層；並且隨電漿功率、進料氣體流量、沈積時間之改變，其聚合層沈積速率亦具有相似之變化趨勢。並且發現當基材膜表面型態為不連續面，有機會製備出類似柱狀結構之沈積層，但隨著沈積層厚度之增加，結構呈現類似柱狀之情形會漸漸轉為不明顯。 藉由正子湮滅光譜技術探討複合膜微結構，並經由VEPFIT軟體分析不同層間S parameter值之變化。由最佳之擬合結果顯示，當PES基材膜表面為緻密皮層(T1)或多孔皮層(T2)，可於三層結構區分得最佳吻合結果；當PES基材膜表面為蕾絲狀結構(T3)，則以四層結構區分得最佳吻合結果。T1及T2基材膜製得具三層結構之電漿複合膜分別為(I)乙炔電漿聚合層、(III)過渡層及(IV)PES基材膜；然而，對於T3基材膜，因電漿聚合反應中，基材膜面孔洞受電漿聚合物填充之效應，造成過渡層前期產生另一層由乙炔電漿聚合物與PES基材高分子共存之混合層(II)。因此更明確地說明基材膜表面型態對電漿沈積層內部結構之影響，特別在過渡層區。
並列摘要
The purpose of this study is to investigate the effect of the substrate surface morphology on the physical structure of plasma-polymerized films. The wet-phase inversion method was used in fabricating the substrate, and by means of changing the membrane formation path, poly(ether sulfone) (PES) substrates with three different surface types (dense skin layer, porous skin layer, and skin-free layer) were formed. Radio frequency-plasma enhanced chemical vapor deposition (RF-PECVD) was the technique applied to conduct the acetylene gas plasma polymerization to deposit plasma-polymerized layer on a substrate with a high homogeneity and good adhesion properties, resulting in the preparation of an asymmetric membrane with a high flux. Scanning electron microscopy (SEM) was used to observe the change in the structure of the plasma-polymerized membrane, and it was combined with the positron annihilation spectroscopy (PAS) technique to investigate the change in the nano-structure of the different layers of the plasma-polymerized composite membrane and to clarify the effect of the substrate surface morphology on the plasma-polymerized layer physical composition. It can be found from the water vapor permeation results that at similar deposited layer thicknesses, different substrate surface morphologies influenced the characteristic permeation rate in the plasma-polymerized composite membrane. With a substrate surface with a lacy-like skin-free structure, a plasma-polymerized layer with a low permeation resistance could be obtained. On investigating the effect of plasma parameters (plasma power, deposition time, acetylene gas feed flow rate, and argon gas amount) on the plasma-polymerized layer structure of different substrate surface morphologies, substrates with different surface morphologies underwent the same change after the plasma polymerization reaction and their polymerized layer deposits had similar thicknesses; changes in the plasma power, feed gas flow rate, and deposition time produced similar trends of changes in polymer layer deposition rates. When the substrate surface morphology was discontinuous, there was a probability to produce a deposited layer with a pillar-like structure; however, with increasing deposited layer thickness, the pillar-like structure would gradually become not obvious. The composite membrane microstructure was investigated further by means of the positron annihilation spectroscopy technique. Based on the VEPFIT software analysis, the change in S parameter values for different layers was shown from best fittings, and with a PES substrate surface with a dense skin layer (T1) or a porous skin layer, a three-layer model produced best fitting results; with a PES substrate surface with a lacy-like structure (T3), a four-layer model gave best fitting results. The structures of T1 and T2 plasma-polymerized composite membranes had three layers: (I) acetylene plasma-polymerized layer, (III) transition layer, and (IV) PES substrate; however, the T3 substrate whose pores were filled with a polymer due to the plasma polymerization reaction had additional pre-transition layer formed by acetylene plasma polymer and PES polymer coexisting in a mixed layer (II). These results explicitly explain the substrate surface morphology influence on the internal structure of the plasma-polymerized deposited layer, especially in the transition layer region.