Effect of differently terminal groups of poly(amido‐amine) dendrimers on dispersion stability of nano‐silica and ab initio calculations

To investigate the effect of differently terminal groups of the lowest‐order generation poly(amido‐amine) dendrimers on dispersion stability of nano‐silica, the four types of G0‐CH₂CH₃ (G0E), G0‐CH₂CH₂CH₂CH₃ (G0B), G0‐NH₂ (G0N), and G0‐COOH (G0C) dendrimer molecules are used to modify the silica based on the dry modification. The zeta potential, the surface charge density, and the storage stability of kinds of modified SiO₂ dispersion systems have been studied. The results show that the effect of carboxyl groups on dispersion stability is stronger than that of the other groups such as the amine and alkyl groups. Mulliken charge distributions of the main active sites are analyzed through the conductor‐like polarizable calculation model (CPCM) on basis of the density functional theory (DFT) method, indicating the formation of chemical bonding between the modifiers and SiO₂ particles. The most stable SiO₂ dispersion system modified by G0‐COOH dendrimer molecule is obtained due to the combined effect including the hydrogen bonding, electrostatic repulsive force, and the steric hindrance of the terminal groups. Copyright © 2015 John Wiley & Sons, Ltd.