You are trying to make a coating of an unknown polymer (what type of
hydrogel?) on an unknown metal surface?
First of all, you need more information about your materials.
Then you should look for a "good" pretreatment of your substrate
(cleaning, etching, etc.).
Then you should check the usual suspects to promote adhesion
I don't see the use of an epoxy adhesive here.
PS: I don't have any experience with epoxies on copper, but regarding
epoxy-acrylates: BPA resins didn't stick very well to copper, formulations
with polar acrylates (e.g. ethylene glycol diacrylates) did better.
Thanks for the information.
To be more specific the hydrogel is based on acrylic acid. I want to
deposit the layer of this hydrogel on to the Cu metal surface. You
suggested one of the adhesion promoter to be the silanes, but is that
final material bioadaptive. I mean is it any way harmful to living
beings (as the application of the final product is in life sciences).
Kindly give some more information.
Information from others is also welcome.
The company I work with has developed a proprietary hydrogel, which
can be used in biochips, medical equipment etc. Aminosilanes are used
as adhesion promoter. There are no problems regarding
bio-compatibility. The silane is fully hydrolysed and bound to
the substrate, no residual monomers are present. There is also
no direct contact of any bio-material to the silane.
Silanes are used in some other life science applications in order
to modify surface properties.
Of course, as with all polymers, you have to carefully control
the amount of monomers present. In contrast to acrylates I have
never heard of any problems with silanes. Epoxy adhesives
will also have a significant fraction of unreacted molecules
present, especially when cured at room temperature.
Theoretically, the acid functions have a strong affinity to metal
surfaces. In my experience this is only true if you have very clean
surfaces => pretreatment! As your application is in life science, more
elaborate pretreatments like the Silicoater method could be
Leaving silanes aside, there are many other ways to improve
adhesion: IIRC chromium give complexes with acrylic acid, perhaps this
might be also an option for you? Phosphonates/Phosphates also strongly
adhere to metals.
Thanks Oliver for much needed useful information.
Could you also tell me the trade name of the aminosilane, which you
suggested and from where can I get the same. Information regarding
tradenames for the adhesion promoters of IIRC Chromium and phosphonates
is also welcome.
I don't have background in materials and thus a very little knowledge of
the same but sometimes, I need to deal with them in my work. So, kindly
give me more information regarding applying of this polymer & adhesion
polymer on to the metal.
Happy New Year!!
Can't help you here - I have to look them up myself.
On the manufacturers' websites you should find information about
applying all the silanes and adhesion promoters.
The aminosilane application is quite easy: because of the amino-function
they catalyse their hydrolysis and condensation and can be cured
by ambient humidity. So, for a very simple pretreatment dissolve
1% Aminopropyltrimethoxysilane in toluene, dipcoat you substrate and
"dry" at ambient conditions. We have also achieved good
results with aqueous formulations "Dynasylan HS-something" (I don't
remember the number) from Degussa/Sivento. Hydrolysis of other silanes
has to be accelarated by an acid, a base or by other means
Hi once again.
As oliver gave me the websites to search the desired silane. So, I have
ordered one with chemical characteristics as
(3-Aminopropyl)trimethoxysilane. The data sheet, I recieved for that
says the following under the Stability & Reactivity;
Materials to avoid:
Reacts violently with water and acids to form heat and methanol.
So what does that mean?
Does that mean after using this as adhesion promoter for my polymer and
the metal plate, can't I use this device to operate in water or any
other solvent. The application of the final device is in liquid medium.
So would this be compatible with that liquid (which, of course, would
Explanation for the same is needed.
Of course not. The silane binds to the surface via silan-oxygen
bridges, in the course of this condensation reaction methanol is
released (self-condensation is also possible).
The amino-function reacts with your polymer. So, ideally none of
these reactivities is maintained in the final product. In reality
some methoxy- and amino-groups will be present, but these will react
slowly with water and usually not effect significantly the properties of your
Usually is is. The stability of your final product in this
environment cannot predicted - you have to test it yourself.
and the catalogue from ABCR offer some introductory information into
the chemistry of silanes.
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