A robust fabrication method for amphiphilic Janus particles via immobilization on polycarbonate microspheres

Janus particles have been studied in various fields of applications such as particulate surfactants in emulsion stabilization, nano-probes and surface catalysts. A major challenge is the preparation of multifunctional, well-defined particles. Here we describe the development of a new, rapid and facile method for the fabrication of amphiphilic Janus particles based on precipitation of a polymer solution via solvent displacement method. Polymethylsilsesquioxane (PMSQ) particles are added to a polycarbonate (PC) solution and subsequently precipitated by the introduction of aqueous surfactant solution under an ultrasonic field. During precipitation, PMSQ particles are assembled onto the PC precipitates to form a PC/PMSQ microsphere. The exposed hemispheres of the PMSQ particles are then selectively silanized by (3-Aminopropyl)triethoxysilane (APTES) to form amine groups on their surface. To obtain amphiphilicity, the functionalized hemispheres are further modified to introduce carboxyl groups. HRSEM confirms the fine embedment of PMSQ particles onto the PC core. EDX and ATR-FTIR analysis confirm the functionalization of the PMSQ particles. Covalent attachment of silica nanoparticles (NPs) to the functionalized hemispheres of the resulting particles along with fluorescent confocal microscopy conclusively proof the successful fabrication of amphiphilic Janus particles. In addition, qualitative macroscopic confirmation of the successful fabrication is provided by the self-assembly of the resulting particles at the interface of the water-chloroform biphasic system.