# Can Liquid CO₂ dissolve plastic

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?

• What kind of plastic? – Dissenter Feb 16 '15 at 23:58
• 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? – DrMoishe Pippik Feb 17 '15 at 3:07

## 3 Answers

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) […]

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.

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.