Surfactants as molecular architects of materials: from interfacial organization to function

Surfactants are versatile molecular tools that control the formation, stabilization, organization and function of materials across multiple length scales, yet the literature treating them remains fragmented across colloid science, soft matter, nanomaterial synthesis, catalysis, energy materials, nanomedicine and sustainable materials chemistry. This Review develops a unifying, materials-centred framework positioning surfactants as molecular architects rather than passive additives, tracing a single causal chain: molecular design determines interfacial adsorption and organization; organization directs nucleation, growth and self-assembly; the resulting dynamic organization determines material formation and structure; and structure, in turn, determines function. We establish a physicochemical taxonomy of surfactant architecture, charge, functionality and origin, and examine the electrostatic, covalent, coordinate, hydrogen-bonding, hydrophobic, it-it and multivalent mechanisms governing interfacial adsorption. We analyze surfactants as active agents in nucleation, growth, templating and self-assembly across noble metals, oxides, semiconductors, silica, carbon materials and hybrid nanostructures, and develop a critical, correlative framework for characterizing the resulting interfaces. We then ask, property by property, what these interfaces are demonstrably known to control-optically, catalytically, electronically, mechanically and energetically-before examining how this control is exploited in catalysis, energy conversion, sensing, environmental technologies, nanomedicine and manufacturing, what it costs biological and environmental systems, how sustainability and regulation constrain it, and what artificial intelligence can and cannot yet contribute to predictive design. Throughout, we distinguish mechanistically established structure-function relationships from those still assumed by empirical analogy, providing a transferable basis for designing next-generation materials with programmable interfaces, controlled functionality and improved sustainability.