Diffusion, phase behavior and gelation in a two-dimensional layer of colloids in osmotic equilibrium with a polymer reservoir

The addition of enough non-adsorbing polymer to an otherwise stable colloidal suspension gives rise to a variety of phase behavior and kinetic arrest due to the depletion attraction induced between the colloids by the polymers. We report a study of these phenomena in a two-dimensional layer of colloids. The three-dimensional phenomenology of crystal-fluid coexistence is reproduced, but gelation takes a novel form, in which the strands in the gel structure are locally crystalline. We compare our findings with a previous simulations and theory, and find substantial agreement.

向原本稳定的胶体悬浮液中加入足量非吸附性聚合物，会因聚合物在胶体颗粒间诱导产生的排空吸引力，引发多种相行为与动力学阻滞现象。本研究针对二维胶体层中的此类现象展开探究。研究复现了晶体-流体共存的三维相态现象学特征，但凝胶化呈现出全新形式——凝胶结构的链状骨架局部呈晶态。我们将本研究结果与既往的模拟与理论工作进行对比，发现二者吻合度极高。