Assessment of commercial poly(ε-caprolactone) as a renewable candidate for carbon capture and utilization

Poly(ε-caprolactone) (PCL) is a cheap and sustainable polymer with long-term degradation (3-4 years) and low temperature transition (Tm = ∼60 °C). We report on the investigation of PCL as a valid green candidate for Carbon Capture and Utilization (CCU). Studies were carried out by two complementary tools: a Sievert-type volumetric apparatus, to thoroughly analyse the CO2 adsorption/desorption process inside the polymer, and Nuclear Magnetic Resonance (NMR) spectroscopy for a deeper study of the molecular dynamics and confinement effects through 13C - pulsed field gradient (PFG) method (self-diffusion measurements), relaxation times (T1) and spectral analysis. The morphology of the solid-state PCL was also investigated by Scanning Electron Microscopy (SEM). The effects of both the physical state and the adsorption process conditions on the PCL's CO2 sorption capabilities were investigated as well as those concerning the cyclic life and the regeneration process. We find that two kind of adsorption sites are present in PCL matrix. Furthermore, PCL show a remarkable and complete thermoreversibility of the CO2 adsorption process, a key condition in view of possible applications in this field.