Flatt Robert J, Schober Irene, Raphael Elie, Plassard Cédric, Lesniewska Eric
Sika Technology, CH-8048 Zurich, Switzerland.
Langmuir. 2009 Jan 20;25(2):845-55. doi: 10.1021/la801410e.
Comb copolymers with an adsorbing backbone and nonadsorbing side chains can be very effective dispersants, particularly when a high ionic strength strongly penalizes electrostatic stabilization. For this reason, they have become essential components of concrete over the past decade. This article examines the steric hindrance characteristics of such polymers through the use of atomic force microscopy (AFM) on calcium silicate hydrate, the main hydration product of Portland cement. It is found that solution and surface properties (hydrodynamic radius, radius of gyration, surface coverage, steric layer thickness) and force-distance curves obtained during AFM measurements can be well described by a scaling approach derived in this paper. This represents the first real quantitative step in relating these properties directly to the molecular structure of such comb copolymer dispersants.
具有吸附性主链和非吸附性侧链的梳状共聚物可以是非常有效的分散剂，尤其是在高离子强度严重不利于静电稳定作用的情况下。因此，在过去十年中，它们已成为混凝土的重要组成部分。本文通过对波特兰水泥的主要水化产物硅酸钙水合物使用原子力显微镜（AFM）来研究此类聚合物的空间位阻特性。研究发现，在AFM测量过程中获得的溶液和表面性质（流体动力学半径、回转半径、表面覆盖率、空间层厚度）以及力-距离曲线可以通过本文推导的标度方法得到很好的描述。这代表了将这些性质直接与此类梳状共聚物分散剂的分子结构相关联的第一个真正的定量步骤。
