IR-polarizing film containing a new quinoline dye and Fe3O4 nanoparticles: optical and thermophysical investigations

Abstract

In the present work, the structure and some molecular properties of a new substance, monosodium mono(4-(2-(2-(2-chloro-1-(2-(1-(4-sulfonatobutyl)-3,4-dihydroquinolin-2(1H)-ylidene)ethyliden)-1H-inden-3-yl)vinyl)-3,4-dihydroquinolin-1(2H)-yl)butane-1-sulfonate (M), with a strong maximum absorption in the near IR region (λ_max = 764 nm) of the spectrum, was modeled using the Density Functional Theory method (DFT/B3LYP/6-311++G*) and then synthesized. The calculated electronic absorption spectrum of M in dimethylformamide (DMF) by TDB3LYP/6-311++G* method and the experimental spectra of M in DMF and in aqueous medium are presented. The charge delocalization of M has been performed with the help of natural bond orbital (NBO) analysis. The UV, IR, and ¹H NMR spectra of M are presented. On the basis of poly(vinyl alcohol) (PVA), a thermostable polarizer film was developed incorporating the new synthesized dye M and magnetite (Fe₃O₄) nanoparticles (NPs) absorbing in the near IR region of the spectrum (λ_max = 750–812 nm) and with polarization efficiency (PE = 95%) in the absorption maximum. The main spectral polarization parameters (transmittance and optical density) of the stretched colored PVA films with M and M + Fe₃O₄ NPs were measured and discussed. Oriented colored PVA films having the phenomenon of anisotropy of thermal conductivity (λ_∥/λ_⊥) were established. Thermal conductivity in the direction of orientation (λ_∥) is higher than that in the direction of perpendicular orientation (λ_⊥). The developed thermostable IR-polarizer film may be used in laser technologies, polarizing microscopes, circular polarizers, magnetometers, spectropolarimeters and electrical signal sensors.