Hello Sk, I am no HMDS expert, and am talking from memory, so don't take my word for any of this: 1: Yes, I believe HMDS is polar, just by looking at the molecule. 2. and 3: HMDS forms a monolayer on SiO2, glass and hopefully (some) metals, making the surface hydrophobic. Since we're talking of monolayers, the thickness is probably below 1 nm. During sylilation by HMDS, some ammonia may be produced. You will find more info in this reference: F. Deyhimi, J. A. Coles, Helv. Chim. Acta 65, 1752 (1982) Rapid Silylation of a Glass Surface: Choice of Reagent and Effect of Experimental Parameters on Hydrophobicity http://onlinelibrary.wiley.com/doi/10.1002/hlca.19820650610/abstract On Thu, Nov 21, 2013 at 8:17 PM, Sk Fahad Chowdhury < sk.chowdhury.fahad@gmail.com> wrote: > Hi > > I have a few questions about hexamethyldisilazane or HMDS > (CH3-Si-NH2-Si-CH3) > > 1. 1. Is HMDS a polar molecule? Is there any dipole present? > electronegativity values of constituents are : H 2.2, C 2.55, Si 1.9, N > 3.04. Carbon (2.55) - flourine (4) bonds are polar because of their > electronegativity difference. > > 2. 2. How thick can HMDS on top of SiO2-Si be when it is dried in air > from a liquid state? Can the thickness of HMDS be determined when it is air > dried? > 3. If HMDS is air dried and some molecules are left in sample, is it going > to be HMDS molecule or it will be something else? Will it release ammonia? > Also will it be a continuous layer or there will be clustering? > > Thanks a lot :) > > regards > > Sk > _______________________________________________ > Hosted by the MEMS and Nanotechnology Exchange, the country's leading > provider of MEMS and Nanotechnology design and fabrication services. > Visit us at http://www.mems-exchange.org > > Want to advertise to this community? See http://www.memsnet.org > > To unsubscribe: > http://mail.mems-exchange.org/mailman/listinfo/mems-talk > -- Gianmario Scotti Researcher Aalto University, Dept. of Materials Science and Engineering http://materials.aalto.fi/en/ Micronova, Tietotie 3 02150 Espoo Finland _______________________________________________ Hosted by the MEMS and Nanotechnology Exchange, the country's leading provider of MEMS and Nanotechnology design and fabrication services. Visit us at http://www.mems-exchange.org Want to advertise to this community? See http://www.memsnet.org To unsubscribe: http://mail.mems-exchange.org/mailman/listinfo/mems-talk