Hydrophile, not absorbing material
Hi! I'm looking for a material that is wetted, preferably by water, but doesn't absorb it. I have a sheet in mind, on top of which a grid of hemispheres of said material is mounted. If water is added on top, it should form a layer on the hemispheres. What happens to the sheet doesn't matter, it can be made out of the same material. Do you know what material I could use? And if not with water, then maybe something for penetrating oil?
To make clear what effect I am looking for: I would like to see a shape of the water film which resembles electrons in a crystal, either interconnected from hemisphere to hemisphere, or a homogenous film, depending on the hemisphere spacing.
Posted Aug 16, 2015, 10:22 AM UTC · edited
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glass wets water, when (very) clean.
On a small scale that might work. I tried to get some lense like behaviour from a puddle of water on a mirror, which I contained with ChapStick. Looked a bit like these videos where they covered a tile with a hydrophobic spray and left a spot in the middle. But cutting hemispheres would be too much for me, especially when I am looking for diameters in the centimeter range.
Ooh, but they might be decorative glass beads, which are somewhat lense shaped.
Edit: Or do you mean with an chemically activated surface? I'm not comfortable with cooking acids in my kitchen.
First thing, to get the expected wetting properties for water, you need to use very clean, deionized water, otherwise polutants will decrease the surface tension. To clean glass beads, use soap, then let rest in a ultrasound bath for approx 1h. (if you do it in your kitchen, mix in boiling water). Then rince with di water until there are no soap bubbles left in when you pour water. It will surprise you how long this takes.
Alternatively, i just thought of the gelatin spheres that you sometimes find if flower pots, they are obviously perfectly wetting, as they are made mostly of water. You can find these is many shops; they come as small dry spheres about 1mm that you soak in water for about 1h and they turn into 1cm spheres.
Never tried DI water, maybe I could use distilled water even. Although I am not sure if the distilled water from the car aisle is not just deionized. Haven't bought the beads, yet.
I already ordered the super absorber spheres. They are often made of sodium polyacrylate. I'm just not convinced that the water layer on their outside is thick enough. They are made to contain the material within, but we'll see.