This study presents an electrostatically regulated strategy for the scalable synthesis of temperature-switchable Janus nanoparticles (JNPs). By employing a Co2+-mediated intramolecular cross-linking method guided by electrostatic interactions, we achieved high-concentration (10-20 mg mL-1) fabrication of monodisperse PEG-b-cPAAc@Co2+-b-PNIPAM, effectively overcoming the low-yield limitations associated with conventional single-chain cross-linking techniques. As temperature-responsive solid surfactants, PEG-b-cPAAc@Co2+-b-PNIPAM Janus nanoparticles enhance the stability of both emulsions and foams at an increased temperature (50 °C) due to the increased hydrophobicity of PNIPAM chains, which promotes their adsorption at the interface and forms a densely packed interfacial film. Foam stabilization experiments demonstrated a 25-fold increase in half-life (16 min at 9 mg mL-1 at 50 °C) compared to surfactant-only systems. Conversely, cooling below the LCST triggers immediate demulsification and foam collapse due to the hydrophilization of PNIPAM. This study not only presents an electrostatic modulation-based cross-linking strategy for the mass production of functional JNPs but also highlights their great potential as intelligent stabilizers in applications such as petroleum recovery and responsive soft materials.
Liu et al. (Wed,) studied this question.