Light-responsive Wormlike Micelles

Abstract

UV/Vis light as a trigger displays a set of advantages over other types of stimuli in terms of its "clean" character, low cost, and precise spatial localization, and for these reasons it has been widely exploited in the development of smart materials. Light-responsive wormlike micelles take advantage of light-induced cis-trans isomerization or dimerization of light-sensitive surfactants or additives containing a suitable chromophore. These changes alter the packing of surfactant molecules in the aggregates and drive micellar transitions between wormlike micelles and other structures, thus tuning the viscoelasticity. This chapter summarizes two types of strategies in manipulating light-sensitive wormlike micelleseither to incorporate light-sensitive additives into classical existing wormlike micellar solutions or to directly introduce light-sensitive functional moieties on the surfactant molecules. In both cases, the worms self-assemble or disassemble upon alternate UV/Vis light irradiation.Keywords Photo-switchable · Light-responsive · Wormlike micelles · Azobenzene · Cis-trans isomerization · Photo-rheology UV/Vis light as a trigger displays a set of benefits over other types of stimuli and thus has been widely exploited in the development of smart materials [1][2][3][4]. Light as a stimulus is relevant to many biological processes, in which optical signals are recorded and transduced as sophisticated biochemical events. In addition, in contrast to redox reagents, pH, stress, or salinity, light is an elegant and non-invasive trigger and can be operated in a clean environment, thus avoiding changes in the composition or thermodynamic conditions. It is a cheap and readily available trigger as a mild energy source. Finally, better than ultrasound and electricity, light can be directed at a precise spatial location; this is particularly valuable in nanoscience and nanotechnology and for medical applications.Light has been used as a trigger by exploiting dimerization, cis-trans isomerization, photo-scission, polymerization, or polarity changes in a range of systems [3]. However, quite obviously, not all reported light-sensitive surfactants