Supercritical CO2 Sorption Within Polymers Used in Medical Devices and Their Packaging

Abstract

Thermodynamic and kinetic aspects of CO2 sorption and the resulting swelling are investigated in several commercial polymer-based medical devices and packaging materials, using in situ FTIR spectroscopy under mild processing conditions (40°C–50°C and 8–20 MPa). At thermodynamic equilibrium, significant CO2 uptake (up to 41% w/w) and volume swelling (up to 62%) are observed in silicones and poly(L-lactide-co-ε-caprolactone) copolymers, whereas limited sorption occurs in polyolefins (polypropylene, high-density polyethylene) and in polyester films coated with low-density polyethylene. These differences are attributed to intrinsic polymer properties; sorption and swelling are favored in polymers combining a highly amorphous structure with elevated chain mobility, and the presence of functional groups with chemical affinity for CO2. Among the studied materials, glycol-modified polyethylene terephthalate exhibits a distinct behavior, characterized by initial CO2 uptake followed by pressure-induced crystallization after several hours of exposure.