Amorphous polymer dynamics and free volume element size distributions from ultrafast IR spectroscopy

Proceedings of the National Academy of Sciences of the United States of America
David J HoffmanMichael D Fayer

Abstract

A method for measuring the size and size probability distribution of free volume regions in polymeric materials using ultrafast infrared (IR) polarization-selective pump-probe experiments is presented. Measurements of the ultrafast dynamics of a vibrational probe (the CN stretch of phenyl selenocyanate) in poly(methyl methacrylate) show that the probe dynamics are highly confined. The degree of confinement was found to be both time-dependent and dependent on the vibrational frequency of the probe molecule. The experiments demonstrate that different vibrational frequencies correspond to distinct subensembles of probe molecules that have different dynamic properties determined by their local structural environments. By combining the degree of dynamical confinement with the molecular size of the probe molecule, the free volume element size probability distribution was determined and found to be in good agreement with the best established experimental measure of free volume. The relative probability of a free volume element size is determined by the amplitude of the nitrile absorption spectrum at the frequency of the measurement. The inhomogeneous broadening of the spectrum was linked to the vibrational Stark effect, which permits ...Continue Reading

References

May 25, 2005·The Journal of Chemical Physics·Howe-Siang TanM D Fayer
Jan 6, 2006·The Journal of Chemical Physics·Y L A Rezus, H J Bakker
Apr 3, 2008·Proceedings of the National Academy of Sciences of the United States of America·David E MoilanenMichael D Fayer
Mar 28, 2012·The Journal of Physical Chemistry. B·Nicholas M LevinsonSteven G Boxer
Jun 15, 2012·Journal of the American Chemical Society·Sayan BagchiSteven G Boxer
Aug 12, 2014·Physical Chemistry Chemical Physics : PCCP·Luuk J G W van WilderenJens Bredenbeck
Jun 8, 2015·The Journal of Chemical Physics·Patrick L KramerMichael D Fayer
Sep 15, 2015·Journal of the Optical Society of America. A, Optics, Image Science, and Vision·Sjoerd Stallinga
Jun 22, 2016·Physical Chemistry Chemical Physics : PCCP·Bartosz BłasiakMinhaeng Cho
Oct 19, 2017·The Journal of Physical Chemistry. B·David J Hoffman, Michael D Fayer

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Citations

Jun 25, 2020·Proceedings of the National Academy of Sciences of the United States of America·Edward W Castner
Dec 3, 2020·The Journal of Chemical Physics·David J HoffmanMichael D Fayer
Feb 26, 2021·Journal of the American Chemical Society·Sebastian M Fica-ContrerasMichael D Fayer
Aug 3, 2021·The Journal of Physical Chemistry. B·Sebastian M Fica-ContrerasMichael D Fayer

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