Dissolving PLA without harm to cured Polyurethane/Silicone

I am currently undergoing a research project involving the development of a prototype using PLA in combination with a surrounding transparent silicone or polyurethane mold. The goal is to make the core of the prototype out of PLA (preferably) or ABS, cast a polyurethane mold around it, and then dissolve the PLA core without any harm to the silicone/polyurethane once cured using a solvent. The end product would be similar to a boiled egg without the egg yolk (yellow part) with a hole at the top.

Are there any popular solvents used today that break down PLA to a liquid-based solution so that it can easily pour out of the prototype while not affecting the structure of the polyurethane/silicone?

According to this post by matador, methyl chloride will dissolve PLA. There is a big list of other solvents that williaap tested here: PLA Finishing Experiment.

WARNING: All of these solvents are toxic, and you shouldn't try to use them unless you have the proper equipment and training. Many of these solvents should only be used in a fume hood.

Many people are interested in a non-toxic solvent that dissolves PLA, but as far as I know, there isn't one.

You could also use HIPS filament and limonene or you could print in wax and remove the wax in boiling water.

The issue with HIPS and with PVA is that it is much more expensive than PLA and ABS (by a factor of 4). Also, methyl chloride is harmful to polyurethane and silicone so it would not be suitable.

Thank you for the responses. Anyone else have an idea of what dissolves PLA but has no effect on molding materials?

If you are out to do something as exotic as what you are implying, the cost of PVA should be nothing compared to these of use. PVA is exactly what you are looking for. It is easily dissolved in hot water, which will not damage your mold. Once you have a mold, make another plug, another mold, etc. One time fee of the PVA is irrelevant.

I heard that tetrahydrafuran is an equivalent to acetone. there are many names for it so im not sure if its in the above or not.

Since PLA is mostly organic I have used hot NaOH with success to clean clogged nozzles.

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Thank you maboo. I am definitely going to study the effects of PLA and Silicone with heated (up to 72 degC) NaOH in my model. I saw that Cube recommends using a "Cubify Ultrasonic Support Removal Tank" for the removal of support material i.e. PLA. Are there any cheaper, equally useful, tanks that can contain heated liquid while also perturbing the liquid over time?

I would also like to thank every one else for the input one more time. All of this information is very beneficial.

Quote
cferraz
Are there any cheaper, equally useful, tanks that can contain heated liquid while also perturbing the liquid over time?

It may not be "equally useful" but it may be good enough: the wiki has a very nice homebuilt hot plate stirrer.

Any ultrasonic cleaning tank should do, too. They are available on ebay starting at <100€, for example.

Maybe Drano has enough lye to dissolve PLA?

Drano might clean a clogged PLA nozzle too.

Make sure you thoroughly remove it from the internal threads,
or your nozzle could experience stress corrosion cracking.

Drano
sodium hydroxide (lye),
sodium nitrate,
sodium chloride (salt), and
aluminum.
[en.wikipedia.org]

Stress corrosion cracking
[en.wikipedia.org]