Impact of Molecular Structure on Zeta Potential and Adsorbed Conformation of .ALPHA.-Allyl-.OMEGA.-Methoxypolyethylene Glycol-Maleic Anhydride Superplasticizers

α-Allyl-ω-methoxypolyethylene glycol -maleic anhydride copolymers were synthesized with side chain lengths n EO from 0-130 and characterized by aqueous GPC.A representation of their molecular conformation (e.g.worm-, brush-or star-like polymers) was developed.The amount of polymer adsorbed on cement rapidly decreases with increasing side chain length n EO .Zeta potential measurements using the electroacoustic method in cement paste with w/c = 0.5 indicate that worm-like copolymers with n EO ≤ 7 adsorb flat ("train" type) and form a densely packed, thin polymer film.In this case, the adsorbed amount of copolymer is high.For star polymers with n EO ≥ 34, preferred orientation of the polymer main chain is perpendicular to the cement surface ("tail" type).The result is a thick polymer layer, with a second electrochemical double layer on top.For star polymers, the adsorbed amount is low because of the higher surface occupancy of horizontally layered side groups.