Stabilizing oil-oil interfaces with mixed-shell polymeric nanoparticles prepared <i>via</i> PISA and the grafting combination.

Zhao, Xi; Peng, Jiani; Shi, Liangliang; Wang, Guoxiang; Gao, Yong · Soft Matter · 2023

basic_science · Level V

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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 <i>via</i> reversible addition-fragmentation chain transfer-based polymerization induced self-assembly in toluene. C<sub>18</sub> alkyl chains were subsequently grafted onto the surfaces of the as-prepared PMMA-P4VP nanoparticles, affording C<sub>18</sub>/PMMA-P4VP MSPNs with P4VP blocks as the core and C<sub>18</sub>/PMMA chains as the mixed shells. MSPNs were utilized as Pickering emulsifiers to prepare non-aqueous Pickering emulsions, where [Bmim][PF<sub>6</sub>] and toluene oils were selected. Two kinds of different Pickering emulsions, [Bmim][PF<sub>6</sub>]-in-toluene and toluene-in-[Bmim][PF<sub>6</sub>], 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.