I tried to deposit some polystyrene thin films by the use of spin coating method. I should mention that the solvent which I used was toluene. The films which I obtained were totally dry. While I need a non-dry thin film.
Would you please give me a hint to approach this problem?
P.S 1: I have tried with different solution concentrations, but the results were the same.
P.S 2: Should I use other solvents such as xylene or chloroform or it doesn't differ?
Dear Ataollah Eivazpour Taher , PS is a solid, and when you use a solution of it for spin-coating, the solvent is readily evaporated, specially if this solvent is quite volatile, such as toluene or chloroform. So it is completely normal that your films get dry. By using different concentrations of PS while keeping all the other parameters (mainly the rpm of the spin-coater) will affect only to the thickness of your film (low concentrations of PS will give you thinner films and high concentrations of PS will provide thicker films).
Xylene is quite toxic, irritant and smells badly, so if you decide to use it handle with care and in a fume-hood and with proper personal protections (gloves...)
Its behaviour should be very similar to toluene (volatility- vapour pressure) so probably you will get dry films of PS anyway.
I imagine you need a wet surface because you are planning to attach it to something, may be you could try to expose your dry film to the vapours of toluene for a few minutes, this could start to dissolve the surface of your film and it would become tacky to stick to another surface.
Hope it helps.
Further the suggestion from Manuel, you could try to use high boiling point solvents which can also dissolve P.S.
Dear Ataollah Eivazpour Taher , you could drop down the spin-coating rate and time, like (1000rpm, 30s). This may help you to get a wet film. Additionally, as mentioned by the former scientist, high BP solvents are recommended, such as chlorobenzene (BP-131), dichlorobenzene(BP-180), etc.
Best
I agree with @you chen. You can increase the amount of solution or you can try coat multiple times on same substrate
Thanks a lot for your useful and valuable tips dear Xuhua Wang , Manuel Gómez , You Chen , and Hasan Sarigül
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