Janus Polymeric Giant Vesicles on Demand: A Predictive Phase Separation Approach for Efficient Formation.

Janus particles, with their intrinsic asymmetry, are attracting major interest in various applications, including emulsion stabilization, micro/nanomotors, imaging, and drug delivery. In this context, Janus polymersomes are particularly attractive for synthetic cell development and drug delivery systems. While they can be achieved by inducing a phase separation within their membrane, their fabrication method remains largely empirical. Here, we propose a rational approach, using Flory-Huggins theory, to predict the self-assembly of amphiphilic block copolymers into asymmetric Janus polymersomes. Our predictions are experimentally validated by forming highly stable Janus giant unilamellar vesicles (JGUVs) with a remarkable yield exceeding 90% obtained from electroformation of various biocompatible block copolymers. We also present a general phase diagram correlating mixing energy with polymersome morphology, offering a valuable tool for JGUV design. These polymersomes can be extruded to achieve quasi-monodisperse vesicles while maintaining their Janus-like morphology, paving the way for their asymmetric functionalization and use as active carriers.