Electrostatic stabilization is based on the repulsion between equally charged particles. By considering the combination of van der Waals attractions and electrostatic repulsion Derjaguin, Landau, Verwey, and Overbeek successfully proposed a theory to describe the electrostatic stabilization of colloidal nanoparticles. Even though some of the assumptions in the DLVO theory, which is named after the scientist, such as infinitely flat surface or constant charge density of the particles, were far from reality, it explained well the interaction between two approaching particles and is widely accepted by the science community. However, there is no report of using electrostatic solely to stabilize the CuO nanoparticles prepared in the liquid phase. Instead, most groups used various surfactants to provide the steric barrier or to combine both mechanisms to achieve the best result in preventing the CuO nanoproduct from aggregation. Typically, surfactants have a hydrophilic head and a hydrophobic tail. The polar charges of surfactants are absorbed onto the surface of nanoparticles, while the hydrophobic tail provides the steric repulsion to stop agglomeration. To provide sufficient repulsion between nanoparticles, the length of the stabilizer needs to be significantly longer than the characteristic size of the nanoparticles. Also, the polar head must have a tight bonding with nanoparticles. That is the reason why stabilizers are often high molecular-weight polymers. Depending on the nature of each different polymer, another beneficial effect that surfactant may bring is to increase the viscosity of the liquid media and thus minimize the rate of coarsening, as presented in the previous part. If you are looking for high quality, high purity, and cost-effective copper oxide, or if you require the latest price, please email contact mis-asia.