Whitby Catherine P, Scales Peter J, Grieser Franz, Healy Thomas W, Kirby Glen, Lewis Jennifer A, Zukoski Charles F
Particulate Fluids Processing Centre, School of Chemistry and Department of Chemical and Biomolecular Engineering, University of Melbourne, Melbourne, Victoria 3010, Australia.
J Colloid Interface Sci. 2003 Jun 1;262(1):274-81. doi: 10.1016/S0021-9797(03)00179-6.
The effects of a poly(acrylic acid) (PAA)-poly(ethylene) (PEO) comb polymer dispersant on the rheological properties and inter-particle forces in aqueous silica suspensions have been studied under varying pH conditions. The comb polymer was found to adsorb more strongly under acidic than basic conditions, indicating that the PAA backbone of the copolymer preferentially adsorbs onto silica surfaces with the PEO "teeth" extending out from the surface into the solution. In the presence of low concentrations of copolymer, the silica suspensions were stable due to electrostatic repulsions between the silica surfaces. At higher copolymer concentrations and under neutral and basic conditions, where the copolymer interacted only weakly with silica, the suspensions showed a transition from a dispersed to weakly flocculated state and attractive forces were measured between silica surfaces. Under acidic conditions, the silica dispersion also destabilized at intermediate copolymer adsorbed density and then was re-stabilized at higher adsorbed coverage. The silica suspensions were stable at high copolymer coverage due to steric repulsions between the particles. The destabilization at intermediate coverage is thought to be due to polymer bridging between particles or possibly depletion forces.
研究了聚丙烯酸（PAA）-聚乙烯（PEO）梳状聚合物分散剂在不同pH条件下对二氧化硅水悬浮液流变学性质和颗粒间作用力的影响。发现梳状聚合物在酸性条件下比碱性条件下吸附更强，这表明共聚物的PAA主链优先吸附在二氧化硅表面，PEO“齿”从表面延伸到溶液中。在低浓度共聚物存在下，由于二氧化硅表面之间的静电排斥，二氧化硅悬浮液是稳定的。在较高的共聚物浓度下以及在中性和碱性条件下，共聚物与二氧化硅的相互作用较弱，悬浮液显示出从分散状态到弱絮凝状态的转变，并且在二氧化硅表面之间测量到了吸引力。在酸性条件下，二氧化硅分散体在共聚物吸附密度处于中间值时也会失稳，然后在较高的吸附覆盖率下重新稳定。由于颗粒之间的空间位阻排斥，二氧化硅悬浮液在高共聚物覆盖率下是稳定的。中间覆盖率下的失稳被认为是由于颗粒之间的聚合物桥连或可能的排空力。
