Effects of the PEG length of polycarboxylate-based terpolymers on their dispersion properties

Abstract

Polycarboxylate-based terpolymers with different PEG length, PAE-Na, were synthesized by free radical emulsion polymerization. The monomers are Poly(ethylene glycol) monomethyl ether monomethacrylate (PMEM, Mn=950g/mol, 500g/mol and 300g/mol), 2-ethylhexyl acrylate (2-EHA) and acrylic acid (AA), respectively. The structures of terpolymers were characterized by 1H NMR and FT-IR. This particular molecular structure of terpolymers guarantees its good dispersibility. Here, PAE-Na terpolymers were used as dispersant and CaCO3 as solid suspension to calculate the dispersion amounts (DAs) by means of titration method. PAE-Na terpolymers with different PEG length show great differences in DAs. Furthermore, the particle size distribution (PSD) and transmission electron microscopy (TEM) were carried out to evaluate the particle size of CaCO3 suspensions. The experiment results show that the dispersibility of terpolymers has an increasing trend while increasing the PEG side chain length. Based on the theory of Flatt and Scaling law, the molecule size of terpolymers with different length of PEG side chain was calculated. The Flory energy as a function H was calculated when two particles approach. Finally, the anti-redepositing power of 3# terpolymer was investigated. The result shows that 3# terpolymer has strong anti-redepositing power. This study may help elucidate the mechanism of dispersion and develop structure-property relationships which could provide theoretical guidance in the design of molecular structure in the practical application.