Structure and stability analysis of biocompatible hydroxyapatite reinforced chitosan nanocomposite

Abstract

Nano‐hydroxyapatite has been used in multifunctional potential clinical applications where certain particle size distribution and morphology are required. The hydroxyapatite/chitosan composites were prepared using in situ co‐precipitation technique, influence of the reaction temperature on the crystallization and particle growth of the synthesized nano‐hydroxyapatite were examined. It was observed that the increase in synthesis temperature had a great influence on particle size and crystal structure of nano‐hydroxyapatite, whereas, the low temperature showed inhabitation of the hydroxyapatite growth in c‐direction and low crystallinity which was confirmed using XRD and electron diffraction pattern of TEM micrographs. The molar ratio of the bone‐like apatite layer for composite prepared at 70°C was higher was higher than the composites prepared at lower temperatures (40°C and −5°C). The AFM images of −5°C, 40°C, and 70°C n‐HAp/CTS composite display presence of CTS rich domains. These CTS rich and domains are made of smaller globular shaped particles in which, n‐HAp particles are embedded in the polymer matrix. The SBF degraded AFM surface topography of the composites shows the CTS is degraded fast rather the n‐HAp. The elastic modulus determined from nanoindentation of −5°C, 40°C, and 70°C n‐HAp/CTS composites are 17.91, 24.56, and 30.62 GPa respectively. Hardness values of the three composites in the same order were found to be 0.86, 1.35, and 1.74 GPa, respectively. Macro‐mechanical tests showed significant enhancement in elastic modulus, coefficient of friction and hardness of 70°C n‐HAp/CTS composites over −5°C and 40°C n‐HAp/CTS. However, the SBF degraded samples also performed moderate improvement in nanomechanical property. POLYM. COMPOS., 39:E573–E583, 2018. © 2018 Society of Plastics Engineers