Highly efficient and selective infrared absorption material based on layered double hydroxides for use in agricultural plastic film

An aminotrimethylenephosphonic acid (ATMP, C3H12NO9P3) with strong IR absorption in the range from ca. 7.7 to 11 μm was intercalated into layered double hydroxides (LDH) host by anion-exchange method using Mg2Al–NO3 LDH as the precursor. The prepared product was characterized using inductively coupled plasma emission spectrometer (ICP), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM) as well as thermogravimetry and differential thermal analysis (TG–DTA). The observed expansion of interlayer spacing of the LDH in the XRD pattern and the disappearance of the FT-IR absorption band for NO3– anions found in the precursor suggest that the guest anions have been successfully intercalated into the LDH interlayer spacing to form organic–inorganic composite. Intercalation in the LDH host improves the thermal stability of the ATMP. When it is incorporated in low density polyethylene (LDPE) film, furthermore, the ATMP intercalated LDH significantly enhances the IR absorption ability of the LDPE film, in particular, the IR selectivity in the range 9–11 μm, which is the main wavelength range of IR irradiation from the earthʹs surface to the atmosphere at night. In addition, the composite aids to enhance the thermal stability of the LDPE film without negative influence on visible light transmittance and mechanical properties. The intercalated LDH is therefore expected to have practical applications as heat retention additives in agricultural plastic films.