Surface nanodroplets for efficient liquid-liquid microextraction and its application to crystallization of organic compounds = 표면 나노 액적을 이용한 효율적인 액-액 미세 추출 및 유기 화합물 결정화로의 응용

다국어 초록 (Multilingual Abstract)

Crystallization reactions, which are challenging to control in large-scale environments, have been extensively investigated utilizing small droplets as a research medium. Crystallization using conventional droplets achieves crystal growth by relying on evaporation or dissolution, which cannot control the rate of supersaturation. Therefore, this study proposes a methodology for controlling the supersaturation and crystallization of organic molecules by inducing liquid-liquid extraction and dissolution using surface nanodroplets. Surface nanodroplets gradually dissolve in flowing aqueous solution simultaneously with liquid extraction of organic molecules, resulting in supersaturation that leads to nucleation and crystallization. Supersaturation and crystallization were regulated by controlling process parameters such as the concentration of organic molecules in the aqueous solution and the flow rate of the solution, using trimesic acid as a model material. Higher concentrations of trimesic acid (TMA) in solution result in more rapid crystallization, primarily due to the increased driving force for TMA diffusion into surface nanodroplets. In addition, the fast flow rate creates a thin concentration boundary layer around the droplet and accelerates supersaturation by dissolving the droplet faster. As an application, we demonstrated the crystallization of amiodarone in chloroform surface nanodroplets. Furthermore, in this study, multi-component nanodroplets were synthesized using an eco-friendly Green Deep Eutectic Solvent (gDES) composed of thymol and decanoic acid. The extraction performance of gDES-based nanodroplets was demonstrated through the extraction of rhodamine 6G and copper ions. Copper ions were chelated with decanoic acid – a component of gDES – facilitating the rapid crystallization of Cu(II)-decanoate crystals. The results presented in this study have revealed novel application potential for surface nanodroplets, suggesting that they may be applicable to various fields such as the pharmaceutical industry, energy devices, and semiconductors.

목차 (Table of Contents)

• I. Introduction 1
• II. Experimental 4
• II-1. Materials 4
• II-2. Substrate and microfluidic chamber preparation 4
• II-3. Formation of trimesic acid crystal via octanol surface nanodroplets 7
• II-4. Extraction of Amiodarone using chloroform surface nanodroplets 8
• II-5. Formation of gDES surface nanodroplets 9
• II-6. Extraction Cu ions and crystallization of Cu(Ⅱ) decanoate crystals using gDES surface nanodroplets 12
• III. Results and Discussion 13
• III-1. Formation of surface nanodroplets 13
• III-2. Crystallization in single component surface nanodroplets 14
• III-2-1. Liquid-liquid extraction by surface nanodroplets 14
• III-2-2. Nanoextraction-induced crystallization 15
• III-2-3. Influence of initial concentration of TMA in solution 17
• III-2-4. Influence of TMA solution flow rate on crystallization 20
• III-2-5. Hindered crystallization in absence of flow 24
• III-2-6. Application of surface nanodroplets to drug crystallization 26
• III-3. Crystallization in Binary surface nanodroplets 28
• III-3-1. Deep eutectic solvent (DES)-based surface nanodroplet formation 28
• III-3-2. Influence of gDES composition 36
• III-3-3. Crystallization of Cu(Ⅱ) decanoate crystals using DES surface nanodroplets 38
• IV. Conclusion 45
• V. References 47
• VI. Appendix 54
• VI-1. Extraction of Rhodamine 6G using DES surface nanodroplets 54
• VII. Abstract in Korean 60