title: Functionalized carbon nanotube via distillation precipitation polymerization and its application in nafion-based composite membranes.
abstract: 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-shell 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 (-COOH, -PO3H2, and -SO3H) 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.
authors.affiliation: Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University , Tianjin 300072, China.
authors.forename: Guangwei
authors.initials: G
authors.lastname: He
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Shen
authors.initials: S
authors.lastname: Hu
authors.forename: Lingqiao
authors.initials: L
authors.lastname: Li
authors.forename: Zongyu
authors.initials: Z
authors.lastname: Li
authors.forename: Yifan
authors.initials: Y
authors.lastname: Li
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Wu
authors.forename: Xinlin
authors.initials: X
authors.lastname: Yang
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Jiang
keywords: Nafion; carbon nanotubes; composite membranes; distillation−precipitation−polymerization; mechanical properties; proton conductivity under low humidity