Chemical vs. mechanical microstructure evolution in drying colloid and polymer coatings
Chemical vs. mechanical microstructure evolution in drying colloid and polymer coatings
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DOI：
10.1038/s41598-020-66875-0
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发表时间：
2020-06
影响因子：
4.6
通讯作者：
Thitiporn Kaewpetch;J. Gilchrist
中科院分区：
文献类型：
--
作者：
Thitiporn Kaewpetch;J. Gilchrist
胶体基薄膜已被广泛开发用于多种应用，包括化学和电屏障涂层、光子材料、生物材料和药物口服给药。先前的许多研究调查了产生具有所需微观结构的最终部件的均匀性或所需分层的方法。很少有研究能够研究原位干燥过程中的这种微观结构。该实验研究使用高速激光扫描共焦显微镜直接追踪在悬浮液中稳定或在干燥过程中具有吸引相互作用的荧光胶体，以获得干燥过程中微观结构演变的细节。稳定悬浮液中的胶体微观结构在干燥过程中不断演变。这些系统中的微观结构具有特征性的沃罗诺伊多面体分布，该分布由对数正态曲线定义，该曲线具有仅取决于其化学成分的恒定标准偏差。由于与内部对流和毛细管力相关的力学，具有强烈吸引力成分的那些制剂具有异质和非单调的微观结构。在干燥结束时，微观结构重排模式的影响仍然很明显。
Colloidal based films have been widely developed for a wide range of applications including chemical and electrical barrier coatings, photonic materials, biomaterials, and pharmaceutical oral drug delivery. Many previous studies investigate methods to generate uniformity or desired stratification of the final components with a desired microstructure. Few studies have been able to investigate this microstructurein-situduring drying. This experimental study directly tracks fluorescent colloids that are either stable in suspension or have attractive interactions during the drying process using high speed laser scanning confocal microscopy to obtain details of microstructural evolution during drying. The colloidal microstructure in stable suspensions evolves continuously during drying. Microstructures in these systems have a signature Voronoi polyhedra distribution that is defined by lognormal curve having a constant standard deviation that only depends on its chemical composition. Those formulations having strongly attractive constituents have microstructure that is heterogeneous and non-monotonic due to the mechanics associated with internal convection and capillary forces. Toward the end of drying, the influence of the mode of microstructure rearrangements remains evident.