N-phosphonomethyl aminodiacetic acid (PMIDA) was intercalated into the interlayer spacing of layered double hydroxides (LDH) by an anion-exchange method. The intercalated LDHs were characterized by various techniques such as powder X-ray diffraction (XRD), FT-IR spectroscopy, elemental analysis and simultaneous thermogravimetric and mass spectrometry (TG-MS) in details. The results show the formation of Mg2Al-PMIDA LDH based on the expansion of d-spacing from 0.89 nm to 1.22 nm and the disappearance of the characteristic IR absorption band at 1384 cm(-1) for NO3- anions. The incorporation of Mg2Al-PMIDA LDH into the low density polyethylene (LDPE) as an additive enhances the selectivity of IR absorption in the main wavelength region 9-11 mu m for radiant heat loss at night. Mg2Al-PMIDA LDH as a heat-retaining additive has practical application in agricultural plastic films. (C) 2012 Elsevier Ltd. All rights reserved.