Surfactant-mediated formation of polymeric microlenses from interfacial microdroplets

Nano- and micro-scale lenses have a range of potential applications, such as in antireflective layers in photovoltaic or light emission devices, and in super resolution imaging in the near field modes. One of the protocols to mass produce polymeric microlenses is through the polymerization of microdroplets of a monomer precursor that are produced at solid-liquid interfaces by a solvent exchange technique. In this work, we have advanced this protocol by using surfactants. A cationic surfactant was added to the liquid phase for the control over the formation and morphology of polymerisable microdroplets and their resultant microlenses (i.e. the polymerized microdroplets). The results demonstrate that the surfactant could enable the production of polymerizable microdroplets on hydrophilic substrates by the solvent exchange technique, and eliminate the restriction by the substrate wettability on the microlens fabrication. Furthermore, the size distribution and aspect ratio of microlenses could be tuned by the surfactant concentration.