Aumento da absorção óptica e diminuição do bandgap de compósitos de PVDF/Curcuma longa Linn: técnica de UV-VIS

Abstract

This study investigated the influence of Curcuma longa Linn. (CLL) incorporation on the structural and optical properties of poly(vinylidene fluoride) (PVDF) films obtained by the casting method. For this purpose, PVDF films containing different concentrations of CLL were prepared. Subsequently, the samples were characterized by Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy. The FTIR spectra confirmed the incorporation of the plant material into the polymer matrix and indicated an increase in the relative percentage associated with the β phase up to a CLL concentration of 10 wt%. In the UV-Vis region, an increase in absorbance and a reduction in transmittance were observed with increasing CLL content. A shift in the absorption edge from 255 nm for pure PVDF to 414 nm for the composite containing 30% CLL was also observed. Additionally, the optical bandgaps associated with direct and indirect transitions decreased with increasing CLL concentration. Overall, the results demonstrate that the incorporation of the plant material produces significant changes in the structural organization and optical response of the system, highlighting the potential of PVDF/Curcuma longa Linn. composites as materials with composition-dependent tunable properties for optical and photonic applications.