Help: Effect of methanol on silanized glass
prak
I have a question regarding the stability of silanized glass surfaces.
I am using a silanizing agent 3-acryloxypropyl)trichlorosilane for
treating the surface of glass by vapor phase chemistry.
I use this silanizing agent to treat the glass surface with acrylic
groups so that when I spin coat and UV polymerize another acrylate
polymer coating on the glass surface, it would stick to the glass
surface after polymerization.
However, for my experiments, I need to treat the surface with methanol
for a couple of days. I observe that the polymer film of acrylate
detaches from the glass surface inspite of silanizing the glass
surface with acrylic groups. I was hoping it would stick to the glass
via the acryloxypropyl siloxane bond.
I wanted to ask if you had any information on whether the methanol is
known to attack the siloxane bond with the glass? if yes, then do you
know of a better way to treat the glass surface so that the acrylate
coating would stay on it even after the methanol treatment? The
methanol treatment is necessary for my experiments and I cannot use
any other solvent instead of methanol, so the only way I have is to
make the adhesion stronger.
Please let me know if you have any suggestions on using an alternative
silane coupling agent or changing the coupling chemistry. Any other
ideas are also more than welcome.
Thanks in advance,
Prak
rek...@gmail.com
> I wanted to ask if you had any information on whether the methanol is
> known to attack the siloxane bond with the glass? if yes, then do you
> know of a better way to treat the glass surface so that the acrylate
> coating would stay on it even after the methanol treatment? The
> methanol treatment is necessary for my experiments and I cannot use
> any other solvent instead of methanol, so the only way I have is to
> make the adhesion stronger.
Methanol won't attack the siloxane bond (they're only attacked by
base). However, I'm not sure why you selected 3-
(acryloxypropyl)trichlorosilane as a coupling agent other than its
similarity to acrylate. Since acrylates have COO- groups, I'd try a
positively charged silane, like 3-aminopropyltriethoxysilane. There
are abundant procedures online for silanizing glass with APTES, since
this is a common procedure for treating microscope slides. Back when
I used to use APTES, I got good results using toluene as the
silanizing solvent (different than procedures you'll find elsewhere).
Make up a 1% solution and dip the glass for 2-3 hours. Make sure your
glass is extra clean, although if you're a coatings guy surely you
realize this...
prak
Thanks for your post!
I am using the acryloxypropyl group in the hope of forming some
polymer linkage with this group during the radical polymerization of
the triacrylate monomer. Do you think that the ionic bond of the
aminopropyl group with the acrylate will be stronger than that?
Next question I have is: Does it also mean that the trichlorosilane
chemistry for silanization is less effective than the triethoxysilane
or trimethoxysilane chemistry?
Also, I noticed that ethanol as a solvent does not remove the UV
polymerized acrylate film from glass surface while methanol does! This
does not make any sense to me.
Any ideas? Thanks again.
rek...@gmail.com
> polymer linkage with this group during the radical polymerization of
> the triacrylate monomer. Do you think that the ionic bond of the
> aminopropyl group with the acrylate will be stronger than that?
Doubt it...but you'd just have to try.
> Next question I have is: Does it also mean that the trichlorosilane
> chemistry for silanization is less effective than the triethoxysilane
> or trimethoxysilane chemistry?
No, doesn't mean that at all. In fact, trichlorosilanes are much more
reactive with -OH groups on the glass, but they're also sensitive to
atmospheric water (not so much an issue for the smaller chain, polar
trichlorosilanes). Trialkoxysilanes are less reactive but easier to
handle. Your problem seems to be that you're just choosing the wrong
functional group on your silane. Also, -OH groups on glass are rather
sparse so the issue of trichlorosilane vs. trialkoxysilane is probably
moot anyway. Furthermore, if you had an amino group on a
trichlorosilane, it'd spontaneously cyclize and thus 3-
aminopropyltrichlorosilane doesn't actually exist.
> Also, I noticed that ethanol as a solvent does not remove the UV
> polymerized acrylate film from glass surface while methanol does! This
> does not make any sense to me.
Methanol is usually a better solvent than ethanol. It doesn't really
surprise me. I don't know how thick your acrylate film is, but
methanol may be better able to permeate into the acrylate than
ethanol.
prak
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