Polyacrylate-type Super-dispersant Modified Nanoparticles

The dispersing of nanosized particles is a new developing technique, which usually shows special effects. Compared with normal block materials, nanosized particles have several advantages in physical and chemical properties, surface, and interface characteristics. However, nanosized particles have huge specific surface area and surface energy, which easily result to aggregation of nanosized particles and inhibit the effect of nanosized particles. In this thesis, a water-soluble hyperdispersant, which can effectively disperse nanosized particles for a long time, and greatly improve the quality of nanosized paticles, was successfully synthesized. The main results are expressed in the following:1. Based on the surface properties of nanosized particles, the structure characteristics of hyperdispersant, reaction mechanisms, and the design principle of anchoring group and solvatable chain, the n-butyl alcohol, maleic acid, and methyl acrylate were selected as the raw materials, and the ammonium persulphate as the initiator, a suitable relative molecular mass and water-soluble hyperdispersant was synthesized by the esterification and polymerization. The anchoring group is -COO", the solvatable chain is poly(methyl acrylate). The FT-IR was used to identify the functional group in the polymer, and the result indicated that -COOH group presented in the backbone of the polymer, most of the reactants had been polymerized, and the monomers were hard to be found.2. Using the method of uniform design, the relationship between the relative molecular mass and reaction factors were studied by selecting the reactant ratio (MA:MAH), the amount of initiator, and the percent of esterification. Using the uniform design table U₅(5³), the tests were conducted 5 times. The results showed that relative molecular mass increased with both the percent of esterification and the increase of the reactant ratio of MA to MAH. However, the relative molecular mass decreased with the increase of the concentration of initiator. The concentration of initiator is a key factor for the relative molecular mass. The products were used to disperse the nanosized CaCO₃ particles and the dispersity was measured. The results indicated that the dispersibility was influenced by the relative molecular mass, and the best result was obtained with relative molecular mass of about 2450. The viscosimetric result showed that the nanosized CaCO₃ system had the lowest viscosity at the relative molecular mass of about 2450. The nanosized CaCO₃ particles can effectively be dispersed when the percent of hyperdispersant is in the range of 1.0% to 1.5%.3. Nanosized TiO₂ was modified by water-based anionic hyperdispersant in order to obtain steady nanosized TiO₂ aqueous suspension. FT-IR, UV, SEM, sedimentation experiment, and viscosity were used to characterize the dispersibility of TiO₂. The results showed that the hyperdispersant was adsorbed onto the TiO₂ surface successfully; the SEM showed that there was no agminated modified TiO₂ particles and the whole average size was less than 100 nm; the modified nanosized TiO₂ can stably suspended 1152 h in water-system, compared with the pre-modified TiO₂ the dispersibility was increased greatly. The UV experiment showed that the nanosized TiO₂ aqueous suspension had the biggest absorption peak at pH 9.