Comb-like polycarboxylate dispersants (PC) with different side chain lengths ranging from 8—23 nm were synthesized using esterifiedmacromer of methoxypolyethyleneglycol (MPEG)-acrylic acid (AA)

AA and styrene sulfonic sodium (SSS). The molecular structure of PC was analyzed by testing its anionic group content and relative molecular. Experiments were performed to study the influence of the length of PC side chain on dispersion and rheological properties of coal water slurry (CWS). The adsorption behaviors of PC on coal/water interface were analyzed by X-Ray photoelectron spectroscopy (XPS)

which was combined with the Zeta potential and the wettability of PC on coal to investigate the action mechanism of PC dispersions in order to provide the basis for designing more efficient polycarboxylate dispersants. The results showed that the dispersibility of PC500 (n=11) was the best due to its structure of long main chain

short side chains and high anionic group content. The CWS using comb-like PC was represented as pseudoplastic fluid

which was best matched with Herschel-Bulkley model. The monolayer adsorption of PC500 on the coal surface possessed the highest adsorption density (0.638 mg·m-2) as well as the maximum thickness (4.20 nm) with better wettability and the highest Zeta potential on coal. PC500 wearing the proper length of the side chain played the steric hindrance and electrostatic repulsion to disperse CWS by balancing adsorption thickness and Zeta potential. PC500 with the right length of the side chain can reduce Gibbs of CWS to weaken “reunion” among the coal particles while improving dispersibility of CWS.