Sustainable surfactant engineering and microfluidic emulsification for green encapsulation

The growing demand for sustainable and environmentally friendly technologies has spurred interest in bio based green surfactants and microfluidic emulsion systems for controlled release applications. This review explores the integration of green surfactants, defined by biodegradability, low toxicity, and renewable sourcing, with microfluidic platforms to enable precise encapsulation. It outlines the classification and physicochemical properties of green surfactants, emphasizing interfacial behavior relevant to emulsion formation and stabilization. In parallel, microfluidic techniques for droplet generation and encapsulation are examined, with attention to how surfactant properties affect droplet size, uniformity, and encapsulation efficiency. Standardized performance metrics such as critical micelle concentration (CMC), interfacial tension, and droplet size distributions support comparison. Where available, we summarize quantitative comparisons of droplet uniformity, energy use, and water consumption, and we note implications for waste reduction. We also outline regulatory considerations that influence material choice, including Registration Evaluation Authorisation and Restriction of Chemicals, the United States Food and Drug Administration, and the European Union Ecolabel. The objective is to bridge the gap between green surfactant development and industrial applicability in microfluidic encapsulation, offering guidance for formulation and scale up. Articles were selected for relevance, rigor, and recency using Scopus and Web of Science, with inclusion criteria focused on surfactant functionality and microfluidic compatibility. The review closes with future directions, including stimuli responsive surfactants, life cycle assessment (LCA), and artificial intelligence (AI) guided formulation to advance sustainable encapsulation.