Drying of the Silica/PVA Suspension: Effect of Suspension Microstructure
Drying of the Silica/PVA Suspension: Effect of Suspension Microstructure
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DOI：
10.1021/la804112b
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发表时间：
2009-06-02
期刊：
影响因子：
3.9
通讯作者：
Lee, Seung Jong
中科院分区：
文献类型：
--
作者：
Kim, Sunhyung;Sung, Jun Hee;Lee, Seung Jong
颗粒/聚合物/溶剂悬浮体系表现出复杂的微观结构。当悬架系统经历涂覆和干燥等工业过程时，系统会经历微观结构的变化。在这项研究中，我们研究了二氧化硅/聚乙烯醇 (PVA) 悬浮液干燥过程中的微观结构变化，重点是悬浮液稳定性。我们通过调节二氧化硅/PVA悬浮液的pH值（1.5、3.6和9）来控制二氧化硅表面上PVA的吸附量。测量到吸附量随着pH值的降低而增加，并且二氧化硅/PVA悬浮液中的絮凝程度随着pH值的降低而变得更强。然而，通过干燥过程中应力发展的测量和干燥后薄膜微观结构的观察，我们发现，更强烈絮凝的悬浮液在干燥后变成了更分散、更紧密堆积的薄膜。通过评估势能，我们可以推测吸附聚合物在二氧化硅/PVA 悬浮液干燥过程中结构变化中的作用。随着 pH 值降低，吸附的聚合物可能会桥接颗粒并在干燥前形成絮凝悬浮液。当溶剂在干燥过程中蒸发时，吸附的聚合物在接近的颗粒之间引入空间排斥，导致从絮凝到分散的微观结构的变化。这意味着所需的二氧化硅/PVA 薄膜性能和二氧化硅/PVA 悬浮液的微观结构可以通过控制悬浮液中的聚合物吸附来定制。
The particle/polymer/solvent suspension system shows complicated microstructure. When the suspension system experiences an industrial process such as coating and drying, the system experiences microstructural change. In this study, we investigated the microstructural change during the drying of a silica/polyvinyl alcohol (PVA) suspension, with an emphasis on suspension stability. We controlled the amount of PVA adsorption on the silica surface by adjusting the pH (1.5, 3.6, and 9) of the silica/PVA suspension. The amount of adsorption was measured to increase with decreasing pH, and the degree of flocculation in the silica/PVA suspension became stronger with decreasing pH. However, through the measurement of stress development during drying and the observation of film microstructure after drying, we found that the more strongly flocculated suspension became a more disperse, close-packed film after drying. By evaluating the potential energy, we could suggest the role of adsorbed polymers in structural change during the drying of the silica/PVA suspension. As pH decreases, the adsorbed polymers could bridge the particles and lead to a flocculated suspension before drying. As the solvent evaporates during drying, the adsorbed polymers introduce steric repulsion between approaching particles, leading to a change from flocculated to dispersed microstructure. This implies that the required silica/PVA Film performance and the microstructure of the silica/PVA suspension can be tailored through controlling the polymer adsorption in suspension.