Functionalized Carbon Nanotube via Distillation Precipitation Polymerization and Its Application in Nafion-Based Composite Membranes

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• 作者：Guangwei He ; Jing Zhao ; Shen Hu ; Lingqiao Li ; Zongyu Li ; Yifan Li ; Zhen Li ; Hong Wu ; Xinlin Yang ; Zhongyi Jiang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：September 10, 2014
• 年：2014
• 卷：6
• 期：17
• 页码：15291-15301
• 全文大小：632K
• ISSN：1944-8252

文摘

The objective of this study is to develop a novel approach to in situ functionalizing multiwalled carbon nanotubes (MWCNTs) and exploring their application in Nafion-based composite membranes for efficient proton conduction. Covalent grafting of acrylate-modified MWCNTs with poly(methacrylic acid-co-ethylene glycol dimethacrylate), poly(vinylphosphonic acid-co-ethylene glycol dimethacrylate), and sulfonated poly(styrene-co-divinylbenzene) was achieved via surface-initiated distillation precipitation polymerization. The formation of core鈥搒hell structure was verified by TEM images, and polymer layers with thickness around 30 nm were uniformly covered on the MWCNTs. The graft yield reached up to 93.3 wt % after 80 min of polymerization. The functionalized CNTs (FCNTs) were incorporated into the Nafion matrix to prepare composite membranes. The influence of various functional groups (鈭扖OOH, 鈭扨O₃H₂, and 鈭扴O₃H) in FCNTs on proton transport of the composite membranes was studied. The incorporation of FCNTs afforded the composite membranes significantly enhanced proton conductivities under reduced relative humidity. The composite membrane containing 5 wt % phosphorylated MWCNTs (PCNTs) showed the highest proton conductivity, which was attributed to the construction of lower-energy-barrier proton transport pathways by PCNTs, and excellent water-retention and proton-conduction properties of the cross-linked polymer in PCNTs. Moreover, the composite membranes exhibited an enhanced mechanical stability.

Keywords:

carbon nanotubes; distillation鈭抪recipitation鈭抪olymerization; Nafion; composite membranes; proton conductivity under low humidity; mechanical properties