Poly(tetrafluoroethylene) (PTFE or Teflon) is notable for its
nonadhesive and nonreactive character.
Successful surface photochemical modification of Teflon using
liquid 1,2-diaminoethane and λ = 193 nm
ArF excimer laser light was demonstrated. The surfaces were
analyzed by X-ray photoelectron spectroscopy
(XPS), atomic force microscopy, and liquid contact angle and gluing
tensile strength measurements. Due
to the photomodification the originally poor adhesive property of the
PTFE surface was dramatically
improved. Surfaces were glued by epoxy resin and the tensile
strength of gluing increased by 150 times
over that of the unirradiated samples. The surface was metalized
electrolessly with silver on selected
areas following patterned phototreatment. As a result of the
photochemical reaction, hydrophilic and
oleophilic property developed on the surfaces at the same time.
The water and benzene contact angles
decreased from 94° to 40° and from 31° to 0°, respectively.
The removal of fluorine and the incorporation
of both alkyl groups and nitrogen were identified on XPS spectra.
The reaction cross section was determined
from water contact angle and XPS results. It was found to be as
high as (1.3−1.6) × 10-17
cm2. A radical
or a photoinduced electron transfer mechanism is suggested to describe
the photoreaction.