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I know that subcritical and supercritical $\ce{CO2}$ are excellent solvents. I've seen some examples of plastics being damaged by the $\ce{CO2}$ being impregnated into the plastic at very high pressures, but in general would liquid $\ce{CO2}$ be able to dissolve plastic?

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    $\begingroup$ What kind of plastic? $\endgroup$ – Dissenter Feb 16 '15 at 23:58
  • $\begingroup$ Good question; since it is used in commercial dry-cleaning, you know it does not attack plastics used for buttons (unless they have to be removed). Anyone in the dry-cleaning business know? $\endgroup$ – DrMoishe Pippik Feb 17 '15 at 3:07
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From the abstract of Solubility of Polymers and Copolymers in Supercritical $\ce{CO2}$

[…] data to temperatures of 270 °C and 3000 bar […]

Over the same range of conditions, $\ce{CO2}$ cannot dissolve polyethylene, poly(acrylic acid), poly(methyl methacrylate), poly(ethyl methacrylate), polystyrene, poly(vinyl fluoride), or poly(vinylidene fluoride) […]

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Depending upon the plastic polymer Liquid $\ce{CO2}$ I believe It dissolves plastic. The chance of this are low. Here is why:

$\ce{CO2}$ solvent has many desirable properties; technically speaking it is a very ‘weak’ solvent: The polarity, dielectric constant and dipole moment are less than that of most conventional organic solvents. Consequently, high-molecular-weight polymers, proteins and polar molecules are only sparingly soluble or even insoluble in $\ce{CO2}$

Scientist have tried to make this more efficient by adding fluorine to the solvent, Unfortunately, fluorinated surfactants are not a good way to solve the problem, being both expensive and harmful to the environment. This research is ongoing, however.

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Supercritical carbon dioxide or liquid carbon dioxide is a relatively poor solvent for polar molecules. Roughly, it is similar to pentane. If a certain plastic is soluble in pentane, probably, it may dissolve in $\ce{CO2}$.

Whenever we work with supercritical $\ce{CO2}$ (for chromatography), we usually pump a small amount of methanol along with it to increase its solvation power, otherwise most of the molecules will not dissolve in pure supercritical $\ce{CO2}$, except "fatty" molecules.

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