Junk_Enginerd
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What makes for example THF and MEK so much more powerful plastic solvents than acetone etc?
I like experimenting with dissolving plastics, usually for things like gluing and also smoothing 3d prints etc.
A common 3d print plastic is PLA plastic. It's got quite a few very desirable characteristics for 3d printed parts. One issue though is how difficult
it is to dissolve. ABS easily dissolves in acetone, and thanks to this it can be smoothed, softened and glued with acetone.
Literature states that both acetone and ethyl acetate will dissolve PLA, but this is far from true in practice. There's clearly *some* interaction
with these solvents, but it doesn't really go further than make the plastic a tiny bit softer.
THF, MEK, chloroform and other more exotic solvents do it well though. Why is that? I've tried to find patterns in their classification(aprotic, polar
etc) but I'm not really getting it. Is there a simple answer to this?
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fredsci93
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Like dissolves like THF, MEK and chloroform are less polar than acetone so they dissolve plastic, there’s a bit more to it but as a rule polarity
and chemical similarity dictate solubility. as for the PLA not dissolving in acetone or EtAc I'd give it more time to dissolve with agitation as well.
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clearly_not_atara
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I mean basically solubility is a competition between the intermolecular cohesion forces of the solvent + solute and the disorder parameters (entropy)
of the solvent/solute mixture. Acetone and EtOAc have relatively large dipole moments compared to the size of the molecule while THF/butanone have
larger molecules relative to their dipole moments. So I'd go with that as an explanation, however unsatisfying.
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