Transparency can be achieved either by refractive index matching of the particle and solvent or making the particle so small that light does not scatter.  You are doing the former approach with some success.  The latter can be achieved by forming mini emulsion using ultrasonic emulsion preparation.  This type of emulsion has particle size of 20-200 nm, and much less than the wavelength  of visible light and, thus, minimizes the Mie scattering.  Prof. Landfester at Max Planck Institute, Mainz, Germany has published extensively on this technique.  If you combine both, refractive matching and mini emulsion, you might improve the transparency.

Hi Hatsuo,

Thank you for the information, I came to the same conclusion with my supervisor yesterday and saw a few papers on the technique in the field of phase change materials (which is what I am focussing on). I will check out Prof. Landfester!

Cheers,

Angus

Try replacing some of the glycerol with propylene glycol - much less viscous... Not quite such a high RI, but much lower viscosity. Glycerol/water mixtures are only really viscous very close to 100% glycerol.

Trying looking for "transparent emulsion" "refractive index" in Google Scholar. I saw an old review in some obscure cosmetics journal once.

I think you need to bring the oil phase RI down  to get matching without changing the solvent properties of your aqueous phase completely.

Hi Alan,

I previously tried poly ethylene glycol but not your proposed propylene glycol - I will give this a try. Yes I agree I think I will have to lower the RI of my oil phase to avoid such high concentrations of glycerol in my aqueous phase.

Cheers,

Angus