Hi all!! I am new to the group and need some advice.
I have problem with the adhesion of polymer (hydrogel) with metal surface (Could be Cu ). I am planning to use epoxy as adhesive. Could you tell me what other better options could I look for? And which particular epoxy would be better?
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 (silanes etc.).
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.
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 affordable.
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.
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 (e.g. Titanalkoxides).
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 contain water).
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 end-product.
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.