Fourier transform infrared, pump-probe polarization anisotropy, and two-dimensional infrared spectroscopies were used to study the steady-state and time-dependent behavior of carbon dioxide dissolved in three different polymer systems. Gas reorientation dynamics in poly(methyl methacrylate), poly(methyl acrylate), and poly(dimethylsiloxane) were sensitive to the nature of chemical interactions between the gas and polymer, as well as whether the polymer was in a glassy or rubbery phase. The homogeneous dynamics experienced by the asymmetric stretching vibration were found to be fastest for rubbery polymers with weak, nonspecific gas-polymer interactions. Spectral diffusion was absent for the carbon dioxide vibrational mode in glassy poly(methyl methacrylate) but was activated for the chemically similar but rubbery poly(methyl acrylate). The vibrational dynamics are shown to have a direct correlation with the diffusivity of carbon dioxide through the polymer matrices.
Bibliographical noteFunding Information:
Acknowledgment is made to the donors of The American Chemical Society Petroleum Research Fund for partial support of this research (56216-ND6). The authors gratefully acknowledge partial support from the National Science Foundation under CHE-1464416. C.G.P. was supported in part by a Newman and Lillian Bortnick Fellowship. I.C.S. was supported by a National Science Foundation Graduate Student Research Fellowship Grant no. 00039202. The authors thank Prof. Michael Fayer (Stanford University) for helpful discussions about orientational anisotropy measurements. C.G.P. thanks Colin Peterson for helpful advice on polymer systems with appropriate glass-transition temperatures.
© 2021 American Chemical Society.
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.