Microfluidic macroemulsion stabilization through In situ interfacial coacervation of associative nanoplatelets and polyelectrolytes

다국어 초록 (Multilingual Abstract)

This study generated a facile and useful methodology for stabilizing macroemulsions through the in situ coacervation of associative silica nanoplatelets (ASNPs) and poly (acrylic acid) (PAA) at the oil–water (O/W) interface. To produce monodisperse macroemulsion droplets in the length scale near 1000 μm, the inner fluid containing partially positively charged ASNPs and the outer fluid dissolving negatively charged PAA were coflowed through a capillary-based microfluidic channel. The generation of a bilayered coacervate at the O/W interface was confirmed by direct observation of confocal laser scanning microscopy. Dynamic interfacial tension and interfacial rheology measurements revealed that the migration of ASNPs and PAA from each phase to the interface led to the formation of a complex bilayered thin membrane with an enhanced interfacial modulus, thereby structurally stabilizing these large drops. In addition, we demonstrated that adjusting the surface properties of ASNPs by coupling a fluorochemical enabled the production of monodisperse fluorocarbon-in-oil-in-water double macroemulsions. These results highlighted the applicability of our microfluidics-based interfacial coacervation technology in the development of complex fluid products with visual differentiation and drug encapsulation.

국문 초록 (Abstract)

본 연구에서는 유–수 계면에서 자기회합 실리카 나노판형입자 (ASNP)와 폴리 아크릭액씨드 (PAA)의 계면 코아세르베이션을 통해 거대액적을 안정화하는 쉽고 유용한 시스템을 제안한다. 1000 μm에 가까운 균일한 거대액적을 생성하기 위해 부분적으로 양전하를 띤 ASNP를 포함하는 분산상과 음전하를 띤 PAA가 분산되어 있는 연속상을 함께 미세 유체 채널에 함께 통과시켰다. 유–수 계면에서 이중층 코아세르베이트의 형성은 공초점레이저 주사현미경의 관찰에 의해 확인되었다. 동적 계면장력 분석을 통해, ASNP와 PAA가 각 상에서 계면으로 이동에 의한 얇은 이중층의 복합 계면막을 형성된다는 것을 확인하였다. 이어진 계면 유변학 연구에서는 이중층 계면막의 강한 물성이 마크로에멀젼을 성공적으로 안정화 시킬 수 있다는 것을 규명하였다. 또한, 우리는 불소실란의 커플링 반응을 통해 ASNP의 표면 특성을 개질함으로써 F/O/W 이중 마크로에멀젼의 제조 역시 가능하다는 것을 입증하였다. 이러한 결과는 우리의 미세유체기술 기반 계면 코아세르베이션 기술이 화장품 산업에서 복합 유체 제품의 개발이나 제약 산업에서의 약물 캡슐화에 적용될 수 있을을 보여준다.

목차 (Table of Contents)

• Chapter 1. General introduction to microfluidic encapsulation 1
• 1.1 The origin of microfluidics 1
• 1.1.1 Droplet generation mechanism 1
• 1.1.2 Droplet microfluidic device 2
• 1.1.3 Various modes of droplet breakup 3
• 1.2 Microfluidic encapsulation strategy 7
• 1.2.1 Colloidal self-assembly 7
• 1.2.2 Interfacial coacervation 7
• 1.3 Biomedical applications of microfluidic encapsulation 11
• 1.3.1 Drug encapsulation 11
• 1.3.2 Biosensors 11
• Chapter 2. Microfluidic macroemulsion stabilization through in situ interfacial coacervation of associative nanoplatelets and polyelectrolytes 14
• 2.1 Introduction 14
• 2.2 Experimental section 17
• 2.2.1 Materials 17
• 2.2.2 Fabrication of capillary-based microfluidic device 17
• 2.2.3 Synthesis of ASNPs and fluorinated silica nanoplatelets (FSNPs) 20
• 2.2.4 Production of macroemulsion by in situ coacervation 20
• 2.2.5 Characterizations 21
• 2.3 Results and Discussion 23
• 2.3.1 Engineering of interfacial coacervation at the O/W macroemulsion interface 21
• 2.3.2 Optimization of ASNP surface chemistry for effective interfacial assembly 28
• 2.3.3 Verification of solid-like membrane formation via interfacial analyses 32
• 2.3.4 Microfluidic macrodrop generation through in situ interfacial coacervation 34
• 2.3.5 Macroemulsion stabilization with a bilayered interfacial membrane 37
• 2.3.6 Extended in situ interfacial coacervation for production of double macroemulsions 39
• 2.4 Conclusion 44
• References 45
• 논문요약 54