Preparation and characterization of ultra-hydrophobic calcium carbonate nanoparticles

Anionic surfactants based on fatty acids are usually used to modify the particle surface properties of CaCO$_3$ with the aim to enhance its dispersion and compatibility with polymer matrices. In this study sodium oleate was used for the preparation of ultra-hydrophobic CaCO$_3$ nanoparticles using a wet carbonation route. The effect of sodium oleate on the characteristics, particle size, morphology, surface potential, thermal decomposition and hydrophobicity of CaCO$_3$, was investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), Zeta potential, thermogravimetric analysis (TGA) and water contact angle measurement (WCA). The results showed that the addition of 2 wt% sodium oleate helps in reducing the particle size from 2 {\mu}m length scalenohedral particles to 45 nm rhombohedral particles and modifying of the hydrophobic property of CaCO$_3$.