Phase transitions, crystal growth

Conformational sensitivity of tricosane absorption band progressions to polymorphic transformations

S. A. Gur'eva^a, V. A. Marikhin^a, A. K. Borisov^a, E. N. Vlasova<sup>b

a</sup> Ioffe Institute, St. Petersburg
^b Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg

Abstract: The polymorphic transformations of monodisperse tricosane $n$-C$_{23}$H$_{48}$ upon heating were studied using FTIR spectroscopy. A disruption of chain regularity in the lamellae cores was revealed based on temperature-induced changes in the progressions of rocking vibrations of CH$_2$ groups and stretching (skeletal) vibrations of C–C bonds. Thermal activation of various types of conformational defects, located predominantly at the chain ends, was observed. It was established that an increasing number of conformational defects facilitates crystal structure rearrangements upon heating, including transitions between intermediate rotator phases (R$_{\mathrm{V}}$, R$_{\mathrm{I}}$, R$_{\mathrm{II}}$).

Keywords: $n$-alkanes, IR spectroscopy, phase transitions, rotator phases.

Received: 30.09.2025
Revised: 30.09.2025
Accepted: 16.10.2025

DOI: 10.61011/FTT.2025.10.61977.263-25

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