# Solid hydrophilic transparant materials that don't dissolve in water

I am looking for hydrophilic transparant materials which are solid at room temperature and that don't dissolve in water. I need these for an experiment in which I condense droplets on a plate made out of/or coated with the material

Just thinking chemically' I imagine that any polymer with a lot of hydroxyl groups will be hydrophilic (like Polyvinylalcohol), but PVA is water soluble. Polyethylenetereftalate (PET) is reasonable but still has a contact angle around 70 degrees (common polymer contact angles)

Does anybody know transparant materials with contact angles closer to 0 that don't dissolve in water? An additional demand' is that the material does not break easily (like glass)

• Does it have to be a polymer? For example, some very hydrophilic (but insoluble) minerals might have small contact angles: quartz and limestone, for example. – Ben Norris Mar 22 '13 at 18:55
• Not necessarily polymer, but preferably yes. The reason is twofold: the material should not break easily (like glass) and it should be transparant – Michiel Mar 23 '13 at 8:56
• If you do not need chemical stability, cellulose esters like nitrocellulose may work. If you find sheet of mica big enough, it may work too. – permeakra Mar 23 '13 at 17:31

Several commercially available titanium dioxide coatings are available, commonly used to kill bacteria or aid UV stability (I think). When exposed to light, the titanium dioxide has a contact angle of almost 0 degrees.

You should be able to deposit a thin layer on something like a PVA or polycarbonate sheet. The commercial coatings are somewhat expensive, though, as far as I can tell, and the common process for doing it yourself involves heating the surface in a mid-temperature flame for 10-15 minutes which excludes pretty much all plastics I know of that would otherwise be suitable.

• Great suggestion! And this could be made transparent by just coating a sufficiently thin layer I guess? – Michiel Mar 24 '13 at 8:58
• @michielm: There are at least commercial coatings designed for windows, so I'm assuming so. – Aesin Mar 24 '13 at 11:06