I am trying to print PDMS on glass surface but PDMS is spreading on glass. I have already treated hydrophobic but didn't get good results. My main aim is to get good adhesion between PDMS and second surface using printing techniques.
I'm not sure if I clearly understood your question. You are using a machine to deposit PDMS on a glass slide in a specific pattern and you'll later paste this PDMS pattern on another surface, right? And your problem is that when you deposit the PDMS on the glass slide, the PDMS wets the surface of the glass and therefore, instead of keeping the pattern that you were interested in, the printed image seems blurry. Did I get it right? In that case you modified the surface of the glass to make it hydrophobic because it would reduce the drop contact angle of PDMS on the surface. I'd say here that the first strategy would be to treat the glass slide with vapors of trichloro perfluorooctyl silane and make it onmiphobic. That would definitely reduce the interaction between PDMS and the glass surface, BUT the PDMS and the glass won't be pasted efficiently, which means that the PDMS could fall down easily.
If you need to modify the surface in a less drastic way, instead of using trichloro perfluorooctyl silane, you can use something like trichloro octadecyl silane. Nevertheless, the interfacial tension (drop contact angle) is just one parameter. You could also explore changing the viscosity of PDMS. For example, add a very small amount of curing agent to a sample of the uncured PDMS, wait/heat some time and add the rest of the curing agent just before printing.
Finally, there are other things you could try: you could spray a solution with soap in the glass and let it dry; if your printing device allows it, you could place the glass slide on the top of a hot plate to cure the PDMS instantly after deposition; use a frosted/sandblasted glass and make it omniphobic; print on a plastic surface that is already oliophilic; or take the glass slide, buy some varnish and deposit a layer of varnish using the spin coater.
Thank you for your answer Juan Héctor González Estefan
I have successfully deposited PDMS on glass but now issue is the detachment. I tried sacrificial layer of poly acrylic acid but during detachment surface tension of water is high and unable to get high resolution line structure like ( 50um width and 5 um thickness). In this case what should I do?
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