Nano Letters, 23, 4822-4829 (2023) [pdf]

Autonomous Interfacial Assembly of Polymer Nanofilms via Surfactant-Regulated Marangoni Instability

Sung-Joon Park, Myung-Seok Lee, Mehmet Emin Kilic, Junil Ryu, Hosik Park, You In Park, Hyoungsoo Kim, Kwang-Ryeol Lee, Jung-Hyun Lee

Interfacial polymerization (IP) provides a versatile platform for fabricating defect-free functional nanofilms for various applications, including molecular separation, energy, electronics and biomeical materials. Unfortunately, coupled with complex natural instability phenomena, the IP mechanism and key parameters underlying the sutructural evolution of nanofilms, especially in the presence of surfactants as interface regulator, remain puzzling. Here, we interfacially assembled polymer nanofilm membranes at the free water-oil interface in the presence of differently charged surfactants and comprehensively characterized their structure and properties. Combined with computational simulations, an in situ visualization of interfacial film formation descovered the critical role of Marangoni instability induced by the surfactants via various mechanisms in struccturally regulating the nanofilms. Despite their different instability-triggering mechanisms, the delicate control of the surfactants enabled the fabrication of defect-free, ultra-permselective nanofilm membranes. Our study identifies critical IP parameters that allow us to rationally design nanofilms, coating, and membranes for target applications.