Photoluminescent Properties of Composites Based on the Liquid Crystal 5CB with Carbon Nanotubes

We have studied the influence of inorganic particles on the photoluminescent properties of the nematic liquid crystal 5CB in composites based on carbon nanotubes (CNTs) and hybrid nanoparticles consisting of carbon nanotubes and platelets of the organically modified mineral montmorillonite (MMT). We show that the photoluminescence (PL) of 5CB + CNT composites is characterized by excimer emission of the 5CB molecules. Adding carbon nanotubes to the liquid crystal medium leads to a considerable decrease in the photoluminescence intensity, but has practically no effect on the bulk structural alignment in the organic matrix. Hybrid CNT-MMT particles form a uniform coagulation network in the composite with 5CB and significantly disrupt the nematic structure of the liquid crystal. Bent conformations of the 5CB molecules appear which are typical of the liquid crystal monomers. The presence of the indicated 5CB conformers in the system and also the weaker interaction between the liquid crystal and the inorganic filler explain the increase in the photoluminescence intensity for the composite 5CB + CNT-MMT compared with the emission characteristics for the original liquid crystal.