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.