Sonochemical synthesis of nano-hydroxyapatite using natural rubber latex as a templating agent

Natural rubber latex was successfully used as a template in the synthesis of nano-hydroxyapatite (HAp) with the aid of a sonochemical process (20 kHz) at 25 degrees C. The hydroxyapatite precursor was obtained using ultrasonic irradiation for 0, 10, 20, 30, 40, 50 and 60 min, respectively. It was then dried at 70 degrees C and calcined at 600 degrees C for 2 h (3 C/min). The effect of sonication time and Ca:P ratio (1.5 and 1.67) on the properties of the powder was investigated by means of thermogravimetric analysis (TGA), X-ray diffraction (XRD), FT-Raman spectroscopy, transmission electron microscopy (TEM) and surface area analysis (N-2-BET method). A lower temperature of formation for synthesised nano-HAp occurred in the case of a (Ca:P) ratio of 1.5. The study clearly indicated that a smaller diameter (8 nm) of nano-rod-like morphology resulted from a 20 min dose of ultrasonic irradiation at a (Ca:P) ratio of 1.5. A possible mechanism of nano-rod formation is that the short polyisoprene chain may act efficiently as a structure-directing agent playing an important role in the formation of nano-structural hydroxyapatite. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.