Institute of Thermal Process Engineering, Thin Film Technology, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, D-76131 Karlsruhe, Baden-Württemberg, Germany.
J Colloid Interface Sci. 2011 Jul 1;359(1):112-20. doi: 10.1016/j.jcis.2011.03.054. Epub 2011 Mar 25.
Soluble polymer is frequently added to inorganic particle suspensions to provide mechanical strength and adhesiveness to particulate coatings. To engineer coating microstructure, it is essential to understand how drying conditions and dispersion composition influence particle and polymer distribution in a drying coating. Here, a 1D model revealing the transient concentration profiles of particles and soluble polymer in a drying suspension is proposed. Sedimentation, evaporation and diffusion govern particle movement with the presence of soluble polymer influencing the evaporation rate and solution viscosity. Results are summarized in drying regime maps that predict particle accumulation at the free surface or near the substrate as conditions vary. Calculations and experiments based on a model system of poly(vinyl alcohol) (PVA), silica particles and water reveal that the addition of PVA slows the sedimentation and diffusion of the particles during drying such that accumulation of particles at the free surface is more likely.
可溶性聚合物经常被添加到无机颗粒悬浮液中，以提供颗粒涂层的机械强度和附着力。为了设计涂层的微观结构，必须了解干燥条件和分散体组成如何影响干燥涂层中的颗粒和聚合物分布。在这里，提出了一个一维模型，揭示了干燥悬浮液中颗粒和可溶性聚合物的瞬态浓度分布。沉降、蒸发和扩散控制着颗粒的运动，而可溶性聚合物的存在影响着蒸发速率和溶液粘度。结果总结在干燥区图中，这些图预测了随着条件的变化，颗粒在自由表面或靠近基底处的聚集。基于聚乙烯醇（PVA）、二氧化硅颗粒和水的模型体系的计算和实验表明，在干燥过程中添加 PVA 会减缓颗粒的沉降和扩散，从而更有可能在自由表面处聚集颗粒。
