title: Raman Line Imaging of Poly(ε-caprolactone)/Carbon Dioxide Solutions at High Pressures: A Combined Experimental and Computational Study for Interpreting Intermolecular Interactions and Free-Volume Effects.
abstract: In the present study, a Raman line-imaging setup was employed to monitor in situ the CO2 sorption at elevated pressures (from 0.62 to 7.10 MPa) in molten PCL. The method allowed the quantitative measurement of gas concentration in both the time-resolved and the space-resolved modes. The combined experimental and theoretical approach allowed a molecular level characterization of the system. The dissolved CO2 was found to occupy a volume essentially coincident with its van der Waals volume and the estimated partial molar volume of the probe did not change with pressure. Lewis acid-Lewis base interactions with the PCL carbonyls was confirmed to be the main interaction mechanism. The geometry of the supramolecular complex and the preferential interaction site were controlled more by steric than electronic effects. On the basis of the indications emerging from Raman spectroscopy, an equation of state thermodynamic model for the PCL-CO2 system, based upon a compressible lattice fluid theory endowed with specific interactions, has been tailored to account for the interaction types detected spectroscopically. The predictions of the thermodynamic model in terms of molar volume of solution have been compared with available volumetric measurements while predictions for CO2 partial molar volume have been compared with the values estimated on the basis of Raman spectroscopy.
authors.affiliation: Department of Chemical, Materials and Production Engineering, University of Naples Federico II , P.le Tecchio 80, 80125 Naples, Italy.
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Pastore Carbone
authors.affiliation: Institute on Polymers Composites and Biomaterials, National Research Council of Italy , 80078 Pozzuoli , Italy.
authors.forename: Pellegrino
authors.initials: P
authors.lastname: Musto
authors.affiliation: Institute on Polymers Composites and Biomaterials, National Research Council of Italy , 80078 Pozzuoli , Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: Pannico
authors.affiliation: Erlangen Graduate School in Advanced Optical Technologies (SAOT) and Lehrstuhl für Technische Thermodynamik (LTT), Friedrich-Alexander-Universität Erlangen-Nürnberg , 91054 Erlangen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Braeuer
authors.affiliation: Department of Chemical, Materials and Production Engineering, University of Naples Federico II , P.le Tecchio 80, 80125 Naples, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Scherillo
authors.affiliation: Department of Chemical, Materials and Production Engineering, University of Naples Federico II , P.le Tecchio 80, 80125 Naples, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mensitieri
authors.affiliation: Department of Chemical, Materials and Production Engineering, University of Naples Federico II , P.le Tecchio 80, 80125 Naples, Italy.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Di Maio