Spectroscopy of condensed matter

Universal features of the manifestation of the relationship between local and segmental dynamics of polymers at terahertz frequencies in IR spectra

V. A. Ryzhov

Ioffe Institute, 194021 St. Petersburg, Russia

Abstract: Low-frequency IR-spectra of glassy polymers were obtained and analyzed at temperatures from 90 to 400 K. Temperature changes in the IR-spectra in the range from 10 to 140 cm$^{-1}$ show three universal features: low-temperature, corresponding to the torsional-vibrational motion of monomer units, high-temperature, due to the influence of primary relaxation (glass transition) and intermediate, caused by the activation of conformational mobility in chains at a temperature of $\beta$-transition. This versatility extends both to polymers with universal chain-to-chain interactions and to those with hydrogen bonds.

Keywords: IR spectra, excess density of vibrational states, bosonic peak, molecular dynamics, $\alpha$- and $\beta$-relaxations.

Received: 11.11.2022
Revised: 09.12.2022
Accepted: 27.12.2022

DOI: 10.21883/OS.2023.01.54534.4323-22

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