Hi all,
I'm Dabin Xie from Zhincai Tech, a small research-driving company in China. I'm currently trying to modify glass with a single layer of silane whether hydrophobic or hydrophilic, like polymer brushes. I managed to make a hydrophobic brush with Diethoxydimethylsilane bottom up with very mild conditions (acid pH, in IPA), even without any pretreatment of glass slides. But when I tried to do the same with triethoxysilane, it never succeded. I couldn't get any covalent bonding between glass and silane. I read from some research that pretreatment is needed for triethoxysilane coupling such as piranha or plasma treatment. But I want to make the process simple enough for "daily" use. So my questions are:
1) Why is it more difficult for triethoxysilane to react with glass?
2) How important is piranha or plasma treatment for an efficient reaction?
3) Is there any other mild condition I can use for the reaction between triethoxysilane and glass (covalent bonding)?
4) During experiments of Diethoxydimethylsilane, I noticed hydrophilic substances would inhibit reaction greatly, such as peg, or some surfactant with hydroxyl groups, is there any research work I can check with?
Thank you all in advance for your help. If you need me to provide more details about my experiment setup, just let me know.
Dabin
Dabin Xie You may want to dry the glass at elevated temperature (say 250 C) before silane treatment. Always keep the glass in dry conditions. An adhesion promoter can work (use one you can get from a paint shop) but is usually unnecessary. You've identified the cause (hydrophobic or hydrophilic surface - or a mix) of your problem. Exclude moisture from the system.
Alan F Rawle Hi, Alan, thank you for your support. You said moisture was one of the reasons. What do you think creates troubles for the reaction between triethoxysilane and glass? Is it because all 3 ethoxy groups hydrolyze into hydroxyl and crosslink each other and there is less opportunity for the glass surface to access it?
Thank you.
Dabin
Dabin Xie Yes, I would agree. Moisture is the main issue, in my experience. Keep everything clean and moisture-free. Cleaning glass is a real art.
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