Abstract The understanding of the evaporation-drying of multi-solvent-solute containing droplets was advanced with a unique single droplet drying (SDD) approach. Analyzing the drying of dual-solvent droplets revealed two stages of temperature increase and the alteration of solute precipitation behavior, from at droplet surface to at the interior of droplet. When a single-solvent droplet was dried with antisolvent vapor, droplet temperature remained constant along the precipitated solids forming microparticles, despite the simultaneous evaporation of original solvent and antisolvent. Toluene and water droplets during ethanol-vapor-infused drying at 31 °C reached the same constant temperature of 27.5 °C, namely the free-evaporating temperature of ethanol. Mathematical and chromatography analyses showed that the solvent composition kept changing. The changing rate, governed by antisolvent vapor density, could profoundly impact final particle morphology, producing lactose microparticles with five distinct morphologies. The proposed SDD technique enables coupled analyses of drying kinetics and microstructure formation for elucidating complex in-drying mechanisms.

中文翻译：

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在没有和有反溶剂蒸汽注入的情况下干燥多溶剂液滴期间的蒸发和颗粒形成

摘要 使用独特的单液滴干燥 (SDD) 方法推进了对含有多溶剂溶质的液滴蒸发干燥的理解。分析双溶剂液滴的干燥过程揭示了温度升高和溶质沉淀行为改变的两个阶段，从液滴表面到液滴内部。当单溶剂液滴用反溶剂蒸汽干燥时，尽管原始溶剂和反溶剂同时蒸发，液滴温度沿着形成微粒的沉淀固体保持恒定。甲苯和水滴在 31°C 的乙醇蒸汽干燥过程中达到相同的恒温 27.5°C，即乙醇的自由蒸发温度。数学和色谱分析表明溶剂组成不断变化。由反溶剂蒸气密度控制的变化率可以深刻影响最终颗粒形态，产生具有五种不同形态的乳糖微粒。所提出的 SDD 技术能够对干燥动力学和微观结构形成进行耦合分析，以阐明复杂的干燥机制。