Analysis of bijel formation dynamics during solvent transfer-induced phase separation using phase-field simulations

Solvent transfer-induced phase separation (STrIPS) is a versatile and scalable method for the fabrication of bicontinuous interfacially jammed emulsion gels (bijels), a soft material with ample potential in membrane separation and energy storage. STrIPS, however, does not facilitate in situ observation of bijel formation, rendering it difficult to relate the phase separation process to the resulting bijel morphology. To address this issue, a phase-field (PF) model is presented that captures the principle components of STrIPS through relatively simple methods. Comparison with experimental results demonstrates that the PF model accurately describes STrIPS, reproducing morphological trends in a complex experimental system. Simultaneously, the model provides insight into the origin of such morphological features, relating the formation of the bijel structure in STrIPS to relatively slow dynamics of phase separation compared to solvent diffusion. Visualising phase separation during the entire STrIPS process, the PF model can therefore help elucidate the formation mechanisms underlying current STrIPS bijel morphologies, in addition to aiding the fabrication of novel ones.