The influence of surface modification on the physicochemical properties of ceramic membranes

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• 作者：Joanna Kujawa ; Anna Rozicka ; Sophie Cerneaux ; Wojciech Kujawski
• 关键词：Wa ; reversible thermodynamic adhesive work ; 纬g ; surface free energy of glycerol [N  ; m&minus ; 1] ; 纬gD ; dispersive component 纬g [N  ; m&minus ; 1] ; 纬gP ; polar component 纬g [N  ; m&minus ; 1] ; 纬L ; surface free energy of liquid used in measurements ; 纬LD ; dispersive component 纬L ; 纬LP ; polar component 纬L ; 纬LV ; surface interfacial free energy (liquid&ndash ; vapour) [N  ; m&minus ; 1] ; 纬LW ; Lifshitz&ndash ; van der Waals component ; 纬S ; surface interfacial free energy of solid [N  ; m&minu
• 刊名：Colloids and Surfaces A: Physicochemical and Engineering Aspects
• 出版年：20 February, 2014
• 年：2014
• 卷：443
• 期：Complete
• 页码：567-575
• 全文大小：2450 K

文摘

Titania ceramic membranes were efficiently modified with perfluoroalkylsilanes (PFAS). PFAS compounds with different length of fluorine alkyl chain (in the range of 6-12 carbon atoms in chain) were used during experiments. Grafting process efficiency was determined by contact angle measurements of water and glycerol. The highest hydrophobicity was obtained for the membrane grafted by C12鈥攁fter 53 h of modification. The contact angle value was equal to 136虋. The least efficient modification was obtained for the membrane grafted with C8, the contact angle was equal to 126虋 after 53 h of grafting. The contact angle measurements with bipolar substance (glycerol) were also carried out in order to apply the Owens-Wendt method for the determination of the surface free energy (SFE) values of modified membranes. The different mode of PFAS chains attachment to the membrane surface was observed. This phenomena was related to different structure of grafting molecules. The hindrance steric effect was observed for more hydrophobic molecules (C10, C12). The surface grafting process was characterized applying ²⁹Si NMR and TGA techniques. According to obtained results, three possible types of bonding of the hydrophobic chains to the materials surface were determined. Additionally, based on the results, it was found that type of PFAS molecule has a strong influence on the mode of anchored hydrophobic molecules to the surface. It was found that PFAS molecules with shorter fluorocarbon chains are attached mainly by siloxane (T³) and geminal silanol bonds (T²), whereas longer chains are attached mainly by single (T¹) and geminal silanol (T²) bonds.