Dear Zakaria Salmi thank you for posting this interesting technical question. According to the literature, the chemistry of the sol-gel process is based on hydrolysis and polycondensation reactions. The weak acid-base interaction drove the nanoparticle nucleation and growth on the surface. For more information please have a look at this useful link:

https://www.sciencedirect.com/science/article/abs/pii/S0254058412008954?via%3Dihub

For some more detailed information about nucleation and crystal growth please also see the very instructive review article:

Article Mechanisms of Nucleation and Growth of Nanoparticles in Solution

I hope this helps to answer your question. Good luck with your work and best wishes, Rahul Verma

Dear Rahul thanks for the link but it doesn't seem to answer my question (it was about interaction of a cured sol gel coating and an acid, I'm going to change the question for it to be clearer) thank you again

zakaria

Silica dissolution rate is enhanced by various species in the aqueous solution, including organic acids (e.g. citric, tartaric, oxalic, humic) and inorganic cations (e.g. Na, Ca...).

I'm attaching a few abstracts illustrating this statement.

Dear Zakaria Salmi

As the coating material is cured silica and you want to know if it possible for an weak organic acid to (break bonds) in such coating , so let me specify the acetic acid as weak organic acid. In this case, the interaction may recognized as heterogeneous uptake on SiO2 and leads to only reversible molecularly adsorbed acetic acid on silica surfaces and at low saturation coverage without reactions leading to acetate formation. Such surface interaction is physical in nature and going deeper in coating matrix depending on the coatings integrity since with low integrity, the defects are easy path for the acetic acid bulk uptake. This implies that the interaction of silica coatings surface with gaseous or aqueous acetic acid is chemically inert while is physically active to degrade the coatings and so this is the principal cause for coatings degradation.

Best regards

https://ir.uiowa.edu/cgi/viewcontent.cgi?article=5390&context=etd

Dear Pr Emanuel Cooper , Pr Mohammed Hussein j. H. Al'Atia,

thank you so much for those valuable answers I'm going to look at these documents. it helps a lot

zakaria