Tunable Assembling of Soft Polymer Janus Nanoparticle at Liquid Interface*

We present a study on the assembly of polymeric Janus nanoparticles (pJNPs) at the toluene/water interface. The soft spherical polymeric Janus nanoparticles pJNPs, made by cross-linking polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (PS-PB-PMMA), show a high interfacial activity where the preferential affinity of the PMMA to the aqueous phase causes a spreading of the PMMA block at the interface, even though neither component is soluble in water. The Janus character is later tailored by substituting the PMMA domain to poly-tert-butylmethacrylate (PtBMA) or poly(methacrylic acid)(PMAA) to probe the influence of Janus balance (solvophilic-to-solvophobic balance) to areal density of assemblies of JNPs at the liquid interface and the response of the assemblies to a compression. We investigated the influence of structural asymmetry of JNPs on the assembly, packing, stability and responsiveness of pJNP assemblies by varying the PS-to-PB-to-PMMA ratio. We demonstrate the potential of structure one liquid structure in another by using JNPs complex with salt at liquid interface to obtain bi-continuous liquids.