I tried to prepare some PS films using drop casting method. I dissolved 0.1g PS in 10ml THF, heated in a water bath and then drop casted it over a glass slide. The layer gets peel off from the substrate after drying it. Can anyone help me to avoid peel off problem in my coatings?
Dear Raja,
I guess that the problem is not the THF. Wetting is a necessary but not a sufficient condition for adsorption. You have to perform some pre-treatments of the surface. Clean and activate your surface (well-known procedures exist). Perform a silanization with something like trichloro(phenethyl)silane (e.g. straightforward vapour deposition).
Regrads Michael Schmitt
Dear Raja,
I guess that the problem is not the THF. Wetting is a necessary but not a sufficient condition for adsorption. You have to perform some pre-treatments of the surface. Clean and activate your surface (well-known procedures exist). Perform a silanization with something like trichloro(phenethyl)silane (e.g. straightforward vapour deposition).
Regrads Michael Schmitt
Dear Schmitt Sir,
How to clean and activate. whether only trichloro phenethyl silane is used or any other solvents can be used to clean and activate. can you guide me to perform cleaning and activate the surface
What Schmitt pointed out is essentially to avoid the mismatch of surface energy between the PS film and the glass surface. Below is just an example for surface modification: Acetone/Methanol/DI water sonication is necessary to remove dust and organic contaminant from the surface. O2 plasma or UV ozone can be used to terminate the surface with -OH. After that, single atomic monolayer such as OTS can be deposited on top to form a high surface energy surface and the PS can be drop cast to form stable film.
Also make sure you test your film thickness. Below 20 nm it is sometimes to get non-uniform film.
Regards,
Haisheng Zheng
PS is hydrophobic and glass surface is hydrophilic. So, you should make a treatment of glass surface or use some hydrophilic polymer.
If you need PS film only, not a glass coated with PS, you can use Teflon as a substrate
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