Dear all, do you have an idea about the nature of hydrophobic group/function on the surface ? In most cases SiO2 are modified with silanes. If so, simply you have check chemistry related to the hydrolysis of Si-O-SiRR'R''. My Regards

Hi...

Your silica particles should have those functional groups already...they are hydrophilic, I suppose.

Ignaas Jimidar thank you for answering. Yes, you are right, naturally silica have -OH functional group, but I have hydrophobic silica, which doesnot have it. Now the requirement is of hydrophilic so I want to modify hydrophobic silica with this functional group.

Thanks

Dear all, do you have an idea about the nature of hydrophobic group/function on the surface ? In most cases SiO2 are modified with silanes. If so, simply you have check chemistry related to the hydrolysis of Si-O-SiRR'R''. My Regards

Hi;

1- Suspend the hydrophobic silica in the presence of a radical initiator in a solvent. The initiator opens the siloxane bonds on the surface of the particles and allows them to be replaced by hydrophilic functions.

2- Hydrolysis in a basic medium (mineral or organic base) at high temperature (autoclave). The inert siloxane bonds are opened by attack of the base at the temperature and pressure of the autoclave; the hydrophilic functions which are formed from the sites thus opened are generated directly in the autoclave in the case of an aqueous solution of mineral base, or subsequently by acid hydrolysis in the case of the variant carried out in an organic medium.

3- By precipitation of silica on the nanoparticles from precursors of metal alkoxides or metal salts.

4- By coating the nanoparticles of hydrophobic silica with hydroxyl-functional coupling agents.

The proposed techniques 1 and 2 have also been successfully used to convert hydrophobic talc into hydrophilic talc.

With my best regards

Doufnoune RACHIDA Rachida thank you so much for your detailed answer with multiple solutions. I am thinking of using technique #4. I have Poly Vinyl Alcohol (PVA) available which I think would be beneficial for this technique. PVA contains OH group and its coating would convert hydrophobic silica to hydrophilic. Can you recommend some literature as reference for such coating or best solvent to make PVA solution to make this successful.

Thank you.

Hi;

The treatment of silica can be carried out in water at a temperature of 70-90°C. DMSO can also be used for PVA with a low degree of hydrolysis. Surface treatment can also be carried out in methanol or in the water-acetone mixture. Please check the following documents.

With my best regards