LAUSR

Abstract To investigate the effect of side-chain structure of comb-like polycarboxylates (PCE) on conformational properties in salt solutions, PCE with polyethyleneoxide (PEO) of different lengths were synthesized using methallyl polyethylene glycol (MPEG, Mw  = 1200, 2400, 4000). Adding counter-ions (i.e., Na+, Ca2+) to dilute PCE solutions was found to induce a more complicated conformational changes, since the screening of the electrostatic intramolecular repulsion and the different complexation behaviors of Ca2+ with carboxylic groups. Laser light scattering (LLS) and conductivity measurements were used to investigate the conformations of PCE at various pH values. PCE of a long side chain polymer and the sparse grafting studied herein possesses a more coiled polymer backbone due to the intramolecular steric hindrance, which resulted in a more exposed extent of carboxylic groups on the backbone at the same pH values. Obviously, the solution conformation of PCE strongly impacts the accessible carboxylic groups contribution to complexation of the carboxylic oxygen atoms of PCE with Ca2+. In this way it may provide a new insight to design the polymer dispersants. Graphical Abstract