At the first 1 g of HIPS polystyrene thermoplastic polymer was mixed with 10 cc of toluene solution for 1 hour and a half using a magnetic stirrer.
The resulting solution was mixed with 0.2 g of hydrophobic sio2 nanoparticles for 1 hour using a magnetic stirrer.
The solution obtained from the previous step was dispersed under ultrasonic bath ( 5 x 100 second cycles )
Then polydimethylsiloxane Silgar 184 was mixed in a ratio of 10: 1 with the solution obtained in the previous step for 30 minutes.
And then 500 seconds (5x100) again with ultrasonic.
The resulting solution was immersed twice as a coating on aluminum substrates, wood and glass slides.
After 24 hours, the coating was dried in the oven for 30 minutes at 100 degrees
The contact angle of the water drop was 118 degrees (without polydimethylsiloxane) if the contact angle with polydimethylsiloxane was expected to increase but decreased to 100 degrees.
Is there a mistake in the protocol?
Is there a problem with the time it takes to put it in the oven?
Hi Alireza,
Contact angle may be affected by factors such as surface roughness. Adding hydrophobic coatings may sometimes result in lower contact angle if it follows the Wenzel model (lower contact angle for rough materials). https://www.biolinscientific.com/blog/wenzel-equation-how-roughness-is-related-to-wettability
Other deposition methods that results in a smoother surface profile may get the job done.
Hope my comment helps.
Good luck!
Cheers,
Ken
PDMS is not that hydrophobic in itself - the contact angle is below 100.
but you do have a complex system - a polymer blend (which may be phase separated) with added particulates. You are probably going to have to try varying the material mixture and tprocessing steps to find the material and process that gives the results you are after.
Dear Alireza Taheri, please refer to the following documents for better understanding of the contribution of both: PDMS and SiO2, to the contact angle changes. My Regards
https://doi.org/10.1021/acs.langmuir.0c00538
https://doi.org/10.1021/j100816a005
In industry, super-hydrophobic coatings are used in ultra-dry surface applications. The coating causes an almost imperceptibly thin layer of air to form on top of a surface. ... The coating can be sprayed onto objects to make them waterproof.
https://en.m.wikipedia.org › wiki
Superhydrophobic coating - Wikipedia
Do not forget to operate under a tightly close extraction hood as these products are toxic. Then, you rince your particles several times with hexane first, then acetone, ethanol then water. The particles should then be hydrophobic and ready to be spread on any surface to make it superhydrophobic.Apr 23, 2019
https://www.researchgate.net › post
How to make super Hydrophobic coating by using SiO2 nanopowder?
https://pubs.acs.org/doi/pdf/10.1021/acsomega.9b03775,kindly check this link.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7057699/,u can follow this link.
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