This Brief provides an up-to-date overview of smart surfactants and describes a broad spectrum of triggers that induce the formation of wormlike micelles or reversibly tune the morphology of surfactant aggregates from wormlike micelles to another state, or vice versa. Combining the fields of chemistry, physics, polymer science, and nanotechnology, its primary focus is on the design, formulation, and processing of intelligent viscoelastic surfactant solutions, covering the scientific principles governing responsiveness to one or more particular triggers, down to the end-use-driven functions. The first chapter explains why and how surfactants self-assemble into viscoelastic wormlike micellar solutions reminiscent of polymer solutions, while the following chapters show how the response to a given trigger translates into macroscopic rheological changes, including temperature, light, pH, CO 2 , redox, hydrocarbon, etc. The last chapter demonstrates the applications of these viscoelastic assemblies in oil and gas production, drag reduction, biomaterials, cleaning processes, electrorheological and photorheological fluids. Comments and perspectives are provided at the end to conclude this Brief.

This Brief is aimed at chemists, physicists, chemical engineers and nano-scientists who are involved in self-assemblies and applications of surfactants, as well as graduates in physical chemistry.

Yujun Feng , Ph.D., is a professor at the State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan Province, P. R. China.
Zonglin Chu , Ph.D., is a post-doctoral fellow working at the Physical Chemistry Institute, University of Zürich, Switzerland.
Cécile A. Dreiss , Ph.D., is a senior lecturer at the Institute of Pharmaceutical Science, King's College London, UK.

Yujun Feng is currently a Professor at the Polymer Research Institute and State Key Laboratory of Polymer Materials Engineering, Sichuan University. After earning his PhD in applied chemistry from Southwest Petroleum University, China, in 1999, he moved to France to undertake his post-doctoral research at the Laboratoire de Physico-Chimie des Polymères, CNRS/Université de Pau, and at the Institut Français du Pétrole (IFP), respectively. In 2004, he joined the Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, and has been acting as a team leader since then. In September 2012, he relocated to Sichuan University, where he is focusing on soft matter, in particular stimuli-responsive surfactants and polymers. Professor Feng is now serving as an associate editor for the 'Journal of Surfactants and Detergents' published by Springer.

Dr. Zonglin Chu obtained his PhD in applied chemistry from the Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences in 2011. After a year of postdoctoral research on multi-step organic synthesis at the Lab of Organic Chemistry, ETH Zürich, he is currently working on surfaces with special wettability in Prof. Dr. Stefan Seeger's group in the Department of Chemistry, University of Zürich. His research interests lie at the interface of organic synthesis, colloid and interface science, hydrogels, smart materials, and functional surfaces.

Cécile A. Dreiss is a Senior Lecturer in the Institute of Pharmaceutical Science, King's College London, UK. Her research focuses on understanding and exploiting self-assembly in soft matter, spanning colloidal, polymeric and biological systems, by establishing relationships between properties on the macro-scale (bulk behaviour or functionality) and the organization at the nanoscale. She uses neutron and X-ray scattering techniques extensively as well as rheology. Cécile graduated in chemistry and chemical engineering (ENSIC, France). She received her PhD from Imperial College London (chemical engineering) in 2003, after which she took up a 2-year postdoctoral position at the University of Bristol. She then moved b