Epoxy-functional diblock copolymer nanoparticles have been prepared by polymerisation-induced self-assembly using a reversible addition-fragmentation chain transfer aqueous emulsion polymerisation formulation. A poly(glycerol monomethacrylate) (PGMA) chain transfer agent was chain-extended using glycidyl methacrylate (GlyMA) at 50 °C. Varying the mean degrees of polymerisation of the PGMA stabiliser block and the PGlyMA core-forming block resulted in well-defined nano-objects with either spherical or worm-like morphologies. Spherical PGMA-PGlyMA nanoparticles, with a z-average diameter (Dz) of 26 nm and polydispersity index (PdI) of 0.03, were evaluated for their suitability as Pickering emulsifiers for the preparation of oil-in-water nanoemulsions. Initially, macroemulsions were prepared by homogenisation of aqueous particle dispersions with dodecane resulting in droplet diameters in the range 20-40 μm at higher particle concentrations (1-7 wt%), as determined by laser diffraction. Subsequently, the macroemulsions were subjected to high-pressure homogenization to prepare the nanoemulsions. PGMA48-PGlyMA50 particles were found to break-down upon high-pressure homogenization, as no intact particles were observed at the oil droplet surface by transmission electron microscopy (TEM) of the dried nanoemulsions. Crosslinked particles were also prepared using ethylene glycol dimethacrylate (EGDMA), to give a final composition of PGMA48-PGlyMA45-EGDMA5. Importantly, the crosslinked particles had the same Dz and PdI (26 nm, 0.03) as the non-crosslinked particles by DLS. When preparing the nanoemulsions with the crosslinked particles, the particles were easily observed at the nanoemulsion droplet surface by TEM of the dried nanoemulsions, see Figure 1. The reactive epoxy groups can be utilised to produce colloidosomes via crosslinking between adjacent nanoparticles adsorbed at the oil/water interface, and the investigation of various types of crosslinking, from the oil phase and from the water phase will be presented.

Investigating the crosslinking of Pickering nanoemulsions stabilised by epoxy-functional diblock copolymer nanoparticles

254th National Meeting (2017)

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