Liquid-liquid phase separation of immiscible polymers at double emulsion interfaces for configurable microcapsules

Baihui Li; Xiaotong Chen; Yue Zhou; Yue Zhao; Tiantian Song; Xiaoxue Wu; Weichao Shi

doi:10.1016/j.jcis.2023.03.072

Liquid-liquid phase separation of immiscible polymers at double emulsion interfaces for configurable microcapsules

J Colloid Interface Sci. 2023 Jul:641:299-308. doi: 10.1016/j.jcis.2023.03.072. Epub 2023 Mar 14.

Authors

Baihui Li¹, Xiaotong Chen¹, Yue Zhou¹, Yue Zhao¹, Tiantian Song¹, Xiaoxue Wu¹, Weichao Shi²

Affiliations

¹ Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.
² Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China; Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300071, China. Electronic address: weichaoshi@nankai.edu.cn.

PMID: 36934577
DOI: 10.1016/j.jcis.2023.03.072

Abstract

Liquid-liquid phase separation at complex interfaces is a common phenomenon in biological systems and is also a fundamental basis to create synthetic materials in multicomponent mixtures. Understanding the liquid-liquid phase separation in well-defined macromolecular systems is anticipated to shed light on similar behaviors in cross-disciplinary areas. Here we study a series of immiscible polymers and reveal a generic phase diagram of liquid-liquid phase separation at double emulsion interfaces, which depicts the equilibrium structures by interfacial tension and polymer fraction. We further reveal that the interfacial tensions in various systems fall on a linear relationship with spreading coefficients. Based on this theoretical guideline, the liquid-liquid phase separation can be modulated by a low fraction of amphiphilic block copolymers, leading the double emulsion droplets configurable between compartments and anisotropic shapes. The solidified anisotropic microcapsules could provide unique orientation-sensitive optical properties and thermomechanical responses. The theoretical analysis and experimental protocol in this study yield a generalizable strategy to prepare multiphase double emulsions with controlled structures and desired properties.

Keywords: Block copolymer surfactant; Double emulsion; Interfacial tension; Liquid-liquid phase separation; Microcapsule.