UV crosslinker for PVA

I need to make a coating that fulfills the basic points: A)Polymer, solvent, photoinitiator and necesary additives should be transparent or near clear, not very toxic and be compatible with organic pigments.Ideal solvent could be water and polymer could be PVA (alcohol)? B)Once applied over a surface and after drying, selected areas not previously cured with UV, should be water-soluble. C)Coating should include some photoinitiator for crosslinking selected areas under UV of 300-400 nm irradiation to get non water-soluble areas. Does anybody can help me selecting a suitable crosslinker for this application? I previously choosed polymer PVA because I believe is non toxic, forms transparent films which are water soluble but I'm open to any other hint. Thanks in advanced for your help


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PVA is water soluble, but I don't know how you would UV crosslink it.

Since your first sentence suggests that you would be willing to make your own polymer, I'd suggest trying either acrylic acid or some type of acrylamide and then also using a 4-acryloxybenzonephenone as a UV-crosslinkable comonomer (see Polymer Bulletin, Vol. 52, No. 3-4, pages 283-289 for an example of this polymer in an acrylate adhesive). There is some other literature on this comonomer as well as some patents. 3M has one from the 1980's or so that was invented by Taylor.

Acrylamide monomer can be a little bit nasty, so consider substituted acrylamides. N-isopropyl acrylamide has some neat temperature inversions that you can play around with. There is plenty of fresh literature to give you lots of fund ideas as well.


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John Spevacek

Thank you very much John for your hints. As I have a very limited knowledge about polymers I would need your help with the following points: Polyacrylamide is water soluble and if I coat a surface with a mixture of water+ polyacrylamide which type of film is formed when water evaporates. Is it a clear film transparent or a color one? This film once formed is it water soluble before crosslinking? This mixture of polyacrylamide and water is an emulsion and can admit a charge of pigments? Should it compatible with an emulsion of PVAlcohol + pigments? Is there any advantage in using N-isopropyl acrylamide instead of polyacrylamide?


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Polyacrylamide will form a clear film upon drying. There could be slight traces of yellowness, or some haziness, but it would still be regarded as clear.

Once the material is crosslinked, it will still absorb water, but it will be a non-soluble gel. Non-crosslinked material will be soluble and can be washed away.

Polyacrylamide in water will actually be a solution, not an emulsion. An emulsion is a stable mixture of non-soluble droplets in water. They appear as a hazy white liquid, much like milk, also an example of an emulsion.

Adding a pigment successfully will depend on the exact nature of the pigment. Possibilities: a) emulsify it using the polymer as the emulisifier, b)disperse the pigment in alcohol, which could then be added to the water/polymer

Acrylamide is considered a possible human carcinogen

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so I can't recommend that you use it given your limited background in chemistry. That is why I suggested the substituted acrylamide, even if it is more expensive. John

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