Structure and near-infrared spectral properties of mesoporous silica for hyperspectral camouflage materials

Mesoporous silica materials were prepared via a hydrothermal method by adjusting the content of trimethylbenzene (TMB) and PEO-PPO-PEO block copolymer (F127) in mesoporous silica. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy(TEM), nitrogen adsorption–desorption analysis(BET),Fourier transform-infrared spectroscopy (FTIR) and Visible near infrared spectrophotometry (VIS-NIR). The effects of mesoporous structure on the water load capacity and near-infrared spectra were systematically then studied. The results showed that the pore size and volume of the mesoporous silica could be tuned by varying the dosage of TMB and F127. In addition, the hygroscopicity of the mesoporous silica was linearly dependent on the pore size and volume, and the as-prepared mesoporous silica had NIR spectral features similar to those of vegetation leaves. More interestingly, as the water content increased, the water absorption peak of the mesoporous silica in the NIR wavebands was closer to that of natural leaves, showing greater similarity. Finally, camouflage coatings were prepared by using the as-prepared mesoporous silica powder as a functional filler and water-borne polyurethane as an adhesive. The cosine similarity between the camouflage coating and natural leaves reached 98.49%, suggesting that the camouflage coating achieved strong similarity in simulating the reflection spectra of plant leaves, potentially providing a new approach to the design of functional fillers of camouflage materials.