Morphology‐Dependent Aggregation‐Induced Emission of Janus Emulsion Surfactants.

We report a novel stimuli‐responsive fluorescent material platform that relies on an evocation of aggregation‐induced emission (AIE) from tetraphenylethylene (TPE)‐based surfactants localized at one hemisphere of biphasic micro‐scale Janus emulsion droplets. Dynamic alterations in the available interfacial area were evoked through surfactant‐induced dynamic changes of the internal droplet morphology that can be modulated as a function of the balance of interfacial tensions of the droplet constituent phases. Thus, by analogy with a Langmuir–Blodgett trough that enables selective concentration of surfactants at a liquid–gas interface, we demonstrate here a method for controllable modulation of the available interfacial area of surfactant‐functionalized liquid–liquid interfaces. We show that a morphology‐dependent alteration of the interfacial area can be used to evoke an optical signal, by selectively assembling synthesized TPE‐based surfactants on the respective droplet interfaces. A trigger‐induced increase in the concentration of TPE‐based surfactants at the liquid–liquid interfaces results in an evocation of aggregation‐induced emission (AIE), inducing an up to 3.9‐fold increase in the measured emission intensity of the droplets. [ABSTRACT FROM AUTHOR]