I tried to crosslink the polymer on PDMS by UV but while washing the coating comes out easily. Is there any simple method to crosslink the polymer and increase the hydrophilicity of PDMS surface.
Could you explain your chemical and process? Did you coat the PDMS with UV curable polymer and applied UV? You need a covalent bond between PDMS and polymer in general.
Most PDMS should be curable in UV, but you would need to dehydrate the coating material prior to the exposure.
The surface properties of the PDMS, will be dependent on the use, you can look into plasma ashing, this works faster than the UV curing but you also have structural method for promoting mechanical hydrophilic nature.
Hi Chandra
It sounds like you are saying that you cured PDMS, and then you put a UV curable coating on top of the cured PDMS, and then you cured the coating. Now that coating comes off too easily.
If so, the coating is probably just sitting on top of PDMS. Not bonded to the PDMS.
If I were you, I might try functionalizing the PDMS surface first to make it bond to the coating. You could try functionalizing the PDMS with a light oxygen plasma treatment on the PDMS before putting the coating on. You could also try treating the PDMS with UV ozone, but I would try oxygen plasma first.
I think the chemical explanation is that the PDMS has methyl groups at the surface, and they are not bonding to your coating. Oxygen plasma will create some temporary OH groups that are much more active. Just put your coating on quick after the plasma step, because the surface only stays active for a little while.
I hope this helps
Andrew H Cannon, PhD
researchmicrostamps.com
Hi Andrew:
Thanks for your detail explanation. I followed the same procedure with oxygen plasma and getting the expected result but 2-3 days after I am checking the contact angle , the surface turning back to hydrophobic. The slipperiness is gone. I am using Poly(ethylene)-glycol-methylcrylate (PEGMA) and BENZOPHENONE IN ETOH.
Thanks
Chandra
Hi Christopher:
Thank You ! Before UV exposure, I am just dipping it in coating material and exposing it to UV . Why is it necessary to dehydrate the coating material?
Anyone can tell me which photo initiators are suitable to mix with PDMS for UV curing?
- Badges
- Science topic
- Similar topics
- Engineering
- Materials Engineering
- Powders