[Hallu]

Hi,
I'm a researcher studying acoustic radiation pressure on liquid / liquid interfaces and I'm currently working on a DC 200 100 cSt (silicone oil by Dow Corning, it's a pDMS oil, (C2H6OSi)n) / FC72 (Fluorinert liquid, formula C6H14 manufactured by 3M) system, and I want to minimize the interfacial tension (typically I use 300 ml of each liquid, so the interface is about 100 cm²). Unfortunately, I can't find any data about a surfactant that would be soluble in the DC200 silicone oil... Everybody is using water soluble surfactant, or other types of oils (hexadecane, dodecane, mineral oils) soluble surfactant, never silicone oils such as DC200. Do you know any surfactant that would be soluble in DC200, and its CMC if possible ? Or maybe a surfactant soluble in fluorinert FC72 (I'd rather not though, since it's a very expensive liquid) ? I can't change the liquids, because I need very specific acoustic parameters (speed of sound, density).
I've already done a lot of research in surfactant books etc... but noone uses the kind of interfacial system I use. They always have a aqueous phase.

Thanks in advance for your help.

[Hallu]

No one can help me with this ?

[marquis]

I have some experience with dow corning 350/360 (DC350/360) silicone oil.  We don't use a surfactant in it.  However, the test method for DC350/360 uses petroleum ether to wash the silicone off the parts before testing by FTIR.

It sounds like you have a surfactant that works in oils, of which pet ether is a close releative.  One approach might be to add some oil surfactant to the pet ether and then add the pet ether/surfactant to the silicone.

Other solvents that silicone is soluble in are toluene and benzene.  Those are usually avoided for safety issues.

[Hallu]

A fellow scientist has told me that trisiloxane surfactants are definitely soluble in DC silicone oils. Do you know where I can buy some (if possible in Europe) ? I can't find anywhere to buy some... Since I'm not a chemist, is there a difference between the common siloxane surfactants and the trisiloxane surfactants ? Thanks in advance.

[marquis]

You have major companies, like Dow, that may be able to help you.  You can try their technical assistance.  Most often, they are dealing with major customers and won't be interested in your project.

One company I've dealt with in the past is United Chemical Technologies in Bristol PA.  I haven't tried them lately and don't know if they deal internationally.  You might try them and see what they recommend.

Good luck.

[DrCMS]

FC72 (Fluorinert liquid, formula C6H14 manufactured by 3M) system

No C₆H₁₄ is hexane the material you are working on is C₆F₁₄

Everybody is using water soluble surfactant, or other types of oils (hexadecane, dodecane, mineral oils) soluble surfactant, never silicone oils such as DC200. Do you know any surfactant that would be soluble in DC200, and its CMC if possible ? Or maybe a surfactant soluble in fluorinert FC72 (I'd rather not though, since it's a very expensive liquid) ? I can't change the liquids, because I need very specific acoustic parameters (speed of sound, density).
I've already done a lot of research in surfactant books etc... but noone uses the kind of interfacial system I use. They always have a aqueous phase.

Thanks in advance for your help.

Do you understand how a typical surfactant works in an aqueous/organic system?  They have hydrophobic and hydrophilic ends that sit at the interphase and if there is enough surfactant they form micelles.

You seem to have 2 hydrophobic liquids, so standard surfactants will not work in your system.   

Do they just form a meta-stable two-layer system based on density or are they genuinely immiscible?

A fellow scientist has told me that trisiloxane surfactants are definitely soluble in DC silicone oils.

They may well be but they are made for an aqueous/organic system and yours is not.