Stabilizing oil–oil interfaces with mixed-shell polymeric nanoparticles prepared via PISA and the grafting combination

Abstract

The preparation of mixed-shell polymeric nanoparticles (MSPNs) and their stabilized non-aqueous Pickering emulsions was described in this study. Poly(methyl methacrylate)–poly(4-vinylpyridine) (PMMA–P4VP) diblock copolymer nanoparticles with different morphologies including spheres, worms and vesicles were first prepared via reversible addition-fragmentation chain transfer-based polymerization induced self-assembly in toluene. C₁₈ alkyl chains were subsequently grafted onto the surfaces of the as-prepared PMMA–P4VP nanoparticles, affording C₁₈/PMMA–P4VP MSPNs with P4VP blocks as the core and C₁₈/PMMA chains as the mixed shells. MSPNs were utilized as Pickering emulsifiers to prepare non-aqueous Pickering emulsions, where [Bmim][PF₆] and toluene oils were selected. Two kinds of different Pickering emulsions, [Bmim][PF₆]-in-toluene and toluene-in-[Bmim][PF₆], could be formed, depending on the initial location of MSPNs. However, neither of them could be generated when PMMA–P4VP diblock copolymer nanoparticles were adopted as Pickering emulsifiers, indicating MSPNs were better than diblock copolymer nanoparticle precursors in the aspect of stabilizing oil–oil interfaces. The formation mechanisms of different kinds of Pickering emulsions were unraveled in this study.