Phase transition dynamics of HBDBA-MWCNT nanocomposites probed by temperature-dependent Raman spectroscopy

This study investigates the phase behaviour of the nanocomposite of multi-walled carbon nanotubes (MWCNTs) and the liquid crystalline system N-(o-hydroxybenzylidene)-N'-(4-n-alkoxybenzylidene) (HBDBA) using spectroscopic and polarizing optical microscopy techniques. The dispersion behaviour of MWCNTs in the HBDBA matrix as a function of temperature was examined using polarizing optical microscopy (POM). Temperature-dependent Raman spectroscopy was used to observe and assess the effect of MWCNTs on the phase transition behaviour of HBDBA. Distinct Raman spectral signatures were observed for the HBDBA_MWCNT composite compared to pristine HBDBA. In particular, the prominent Raman bands associated with the linking group (NN and CN) and phenyl ring modes were critically analyzed on the variation of temperature to reveal the dynamics of intermolecular and intramolecular interactions during phase transitions. These experimental findings were further supported by the potential energy distribution (PED) calculation of the vibrational modes of the calculated optimized structure of HBDBA using density functional theory (DFT). The results demonstrate that incorporating functionalized MWCNTs alters the intermolecular interaction network of HBDBA, thereby altering both the dynamics and temperature of the phase transition.