Wang Yang,
          Typically we use plasma to produce hydrophilic surfaces and
silanes to produce hydrophobic surfaces.  In time factors I found for
example taking Teflon with a contact angle of 120 degrees, a 1 minute
Argon plasma can produce a 2 to 3 degree surface.  A week later it had
changed to 15 degrees a week later 30 degrees.  Months later it is back
to 120 degrees.  While writing this I conferred with our silane/plasma
engineer.  He agrees with your statement of a week to return to the old
contact angle. Discussing Hydrophilic silanes with our silane expert it
turns out that Gelest has a line of silanes it describes as hydrophilic,
Polar non-Hydrogen bonding.  Of 20 compounds listed about 90% are
cyano's We have not used these compounds so we have no direct experience
or results.  Ken our silane expert is interested in testing one of these
compounds so we may have later news for you.

Bill Moffat, CEO
Yield Engineering Systems, Inc.
203-A Lawrence Drive, Livermore, CA  94551-5152
(925) 373-8353
bmoffat@yieldengineering.com
www.yieldengineering.com