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

详细信息    查看全文

• 作者：Maria Giovanna Pastore Carbone ; Pellegrino Musto ; Marianna Pannico ; Andreas Braeuer ; Giuseppe Scherillo ; Giuseppe Mensitieri ; Ernesto Di Maio
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：September 1, 2016
• 年：2016
• 卷：120
• 期：34
• 页码：9115-9131
• 全文大小：653K
• 年卷期：0
• ISSN：1520-5207

文摘

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.