Janus interfaces with asymmetric wettability: from fundamental chemistry to emerging applications

Janus interfaces consist of chemically asymmetric surfaces that give rise to asymmetric wettability and interfacial transport phenomena. This literature review delves into the current state of Janus materials, encompassing their design principles and fabrication methods such as electrospinning, plasma treatment, dip coating, and spray coating, as well as the underlying mechanisms that govern their unique properties. We consider their innovative uses in the fields of biological medicine, including advanced wound dressings that help in wound healing through the interactive management of exudates, wearable sensors to track real-time sweat biomarkers, and personal thermal management fabrics. We also present the advanced applications of Janus materials in industrial studies, such as oil-water separation, fog harvesting, and desalination. These applications leverage asymmetric wettability to achieve selective permeability and improve interfacial interactions. Moreover, we address the existing issues in scalability and long-term stability and provide a vision for the future trends, such as real-world testing and cross-disciplinary collaborations. This review aims to integrate basic materials science knowledge and applied research to develop interdisciplinary innovations for sustainable, smart solutions in biomedical and industrial contexts.