Modification of amorphous aluminum phosphate with alkyl phosphates

Synthetic amorphous aluminum phosphate (AlPO4) particles were treated with monohexyl, monooctyl, and monodecyl phosphates in acetone, and the resultin g materials were characterized by X-ray diffraction (XRD), transmission ele ctron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, the rmogravimetric and differential thermal analyses (TG/DTA), and adsorption o f N-2. XRD patterns of the modified samples showed a strong diffraction pea k and two weak ones below 2 theta = 15 degrees. The d-values of these peaks linearly increased with elongating of alkyl groups of the phosphates. Afte r the treatment, particle size increased without formation of new particles . These results reveal that a multilayer alternating bimolecular layer of a lkyl phosphates and aluminum phosphate phase is formed on the surface of Al PO4 particles by the modification with alkyl phosphates. The layered struct ure disappeared on outgassing above 300 degrees C, accompanying the removal of alkyl groups, formation of mesopores, and variation of surface structur e. (C) 2000 Elsevier Science Ltd. All rights reserved.