A Color-Changing Biomimetic Material Closely Resembling the Spectral Characteristics of Vegetation Foliage.

ABSTRACT

Multispectral/hyperspectral technologies can easily detect man-made objects in vegetation by subtle spectral differences between the object and vegetation, and powerful reconnaissance increases the demand for camouflage materials closely resembling vegetation spectra. However, previous biomimetic materials have only presented static colors that cannot change color, and camouflage in multiple bands is difficult to achieve. To address this challenge, inspiration is drawn from the color change of foliage, and a color-change model is proposed with active and static pigments embedded in a matrix medium. The color of a composite material is dominated by the colored active pigment, which conceals the color of the static pigments and the color is revealed when the active pigment fades. A color-changing biomimetic material (CCBM) is developed with a solution casting method by adopting microcapsuled thermochromic pigments and chrome titanate yellow pigments as fillers in a base film with polyvinyl alcohol and lithium chloride. A Kubelka-Munk four-flux model is constructed to optimize the component proportions of the CCBM. The material has a reversible color change, closely resembles the foliage spectrum in UV-vis-NIR ranges, and imitates the thermal behavior of natural foliage in the mid-infrared regime. These results provide a novel approach to multispectral and hyperspectral camouflage.