Coaxially Electrospun PVDF-Teflon AF and Teflon AF-PVDF

四氟

Coaxially Electrospun PVDF-Teflon AF and Teflon AF-PVDF Core-Sheath Nanofiber Mats with Superhydrophobic Properties

Palanikkumaran Muthiah,† Shu-Hau Hsu,† and Wolfgang Sigmund*,†,‡
†Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611-6400, and
‡Department of Energy Engineering, Hanyang University, Seoul, South Korea

Received February 19, 2010. Revised Manuscript Received March 26, 2010

This work reports the coaxial electrospinning of poly(vinylidene fluoride) (PVDF)-Teflon amorphous fluoropolymer
(AF) and Teflon AF-PVDF core-sheath nanofiber mats yielding superhydrophobic properties. The coaxial
electrospinning configuration allows for the electrospinning of Teflon AF, a nonelectrospinnable polymer, with the help
of an electrospinnable PVDF polymer. PVDF-Teflon AF and Teflon AF-PVDF core-sheath fibers have been found
to a have mean fiber diameter ranging from 400 nm to less than 100 nm.TEMmicrographs exhibit a typical core-sheath
fiber structure for these fibers, where the sheath fiber coats the core fiber almost thoroughly. Water contact angle
measurements by sessile drop method on these core-sheath nanofiber mats exhibited superhydrophobic characteristics
with contact angles close to or higher than 150
. Surprisingly, PVDF-Teflon AF and Teflon AF-PVDF nanofiber mat
surface properties were dominated by the fiber dimensions and less influencd by the type of sheath polymer. This
suggests that highly fluorinated polymer Teflon AF does not advance the hydrophobicity beyond what surface physics
and slightly fluorinated polymer PVDF can achieve. It is concluded that PVDF-Teflon AF and Teflon AF-PVDF
core-sheath electrospun nanofiber mats may be used in lithium (Li)-air batteries.