Synthesis and fine spectroscopy tuning of the hyperspectral simulation material based on organic anions intercalated Mg-Al layered double hydroxide

Abstract

Organic anions have been intercalated into the interlayer of Mg-Al layered double hydroxides (LDHs) via a hydrothermal method to tune the visible and near-infrared reflection spectrum of hybrid pigments based on LDHs. The prepared samples were analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric-differential scanning calorimetry, visible and near-infrared spectrophotometry, and CIE 1976 L*a*b* color scales. The effects of the intercalated organic anions on the structure, morphology, color, and spectral characteristics of Mg-Al LDH materials were systematically investigated. The results show that the colored anions of acid green (AG) and acid yellow (AY) have been successfully intercalated into the interlayer space of LDHs through the anion displacement process. The visible light reflection spectrum of LDH matrix can be easily tuned by adjusting the intercalated concentration of anions and the relative ratio of AG and AY, which leads to the color of prepared samples changing from the original white into blue, yellow, green, and dark black. Combined with the color adjusting ability of organic anions and the high hydroxyl property of LDH substrate, the typical visible and near-infrared spectral characteristics of natural green plants can be accurately simulated. The correlation coefficient of spectrum shape between the prepared pigment and green plant in the whole range of 400–2500 nm is as high as 0.94. Moreover, the thermal stability of LDH materials is improved by the intercalated organic anions, whose spectral properties can withstand high temperatures of at least 250 °C. The hybrid materials could be used as a functional pigment to prepare green camouflage coatings, showing their potential application in the field of hyperspectral camouflage.