Synthesis of a novel comb-like copolymer used as dispersant in organic solvent and influence of free comb-like copolymer on CaCO3suspension

A novel comb-like copolymer poly (1e)-graft-poly (ε-caprolactone) (SMA-g-PCL, SP), which can be used as an effective CaCO3 dispersant in organic solvent, was prepared via the esterification reaction between SMA and PCL. The structures and compositions of the graft copolymer were determined by Fourier transform infrared spectrometry (FTIR), H-nuclear magnetic resonance (1H NMR), and gel permeation chromatography (GPC), respectively. The influences of free comb-like copolymer on CaCO3 suspension viscosity and rheological behavior were investigated. It was found that the particle-binding bridge generated among CaCO3 particles through hydrogen bonding and/or electrostatic interactions increased the suspension viscosity as well as the depletion flocculation. On the other hand, it was noteworthy that the free comb-like copolymer could make the CaCO3 suspension evolve from shear-thinning fluid or nearly Newtonian fluid into shear-thickening fluid. It was attributed to the formation of a transient network through intermolecular associations between the adsorbed SP and the free polymer chains under the action of shear. Finally, the fitting parameters from the Herschel–Bulkley model were in good agreement with the evolution of the rheological behavior of CaCO3 suspension.