Diblock copolymer worms stabilized pH-responsive Pickering emulsions: An efficient and recyclable platform for Claisen-Schmidt condensation reaction

Pickering emulsions were promising platforms for the heterogeneous reactions due to both their large interfacial areas and high stability, whereas both the product separation and the emulsifier recovery via simple and efficient strategies for remain a concern. In this study, we constructed an efficient and recyclable platform for interfacial catalytic reaction adopting pH-responsive n-decane-in-water Pickering emulsions. Pickering emulsions were prepared employing core cross-linked PEO45-PGMA74 (CCE45G74) diblock copolymer worms as Pickering emulsifiers. CCE45G74 diblock copolymer worms were prepared via the combination of photo-initiated polymerization induced self-assembly strategy and the core covalent cross-linking with ethylenediamine. The prepared n-decane-in-water Pickering emulsions showed a high stability during the storage at the room temperature, whereas a rapid demulsification took place at a lower pH, such as 2.5. Alkali-catalyzed Claisen-Schmidt condensation reactions between benzaldehyde and acetone were conducted in n-decane-in-water Pickering emulsions at 30 °C. The yield of dibenzylidene acetone could reach 99% after 12 h of reaction. The reaction efficiency was far higher than that at the plain n-decane-water (∼30%). This catalytic platform could be repeatedly used for three cycles.