Cross-linking of double oil-in-water-in-oil emulsions: A new way for fragrance encapsulation with tunable sustained release

Abstract

This paper describes a new route to synthesize polymeric capsules with interesting and diverse diffusive and mechanical properties. Such capsules were obtained by free radical cross-linking copolymerization of the intermediate water phase of a double oil-in-water-in-oil (O/W/O) emulsion. Such a strategy allows separating the locus of polymerization from the fragrance-containing compartment. Indeed fragrance molecules are known to be reactive. The encapsulated species, also corresponding to the innermost oil, was a model fragrance composed of more than 10 various molecules usually used in perfumery. In a first step, the double emulsion containing a hydrophilic monomer, either Methacrylamide or Oligo(ethyleneglycol) methacrylate, and a hydrophilic cross-linker, either Tetra(ethyleneglycol) diacrylate or N,N-Methylene-bis-Acrylamide, was formulated. The influence of the cross-linker agent on the feasibility of the double emulsion was examined. Then, in a second part, the polymerization was performed. Four different systems of capsules were developed and compared in terms of diffusive and mechanical properties. We show that changing the monomer /cross-linker couple allowed modulating the capsule properties.

Green Hydrophilic Capsules from Cellulose Nanocrystal-Stabilized Pickering Emulsion Polymerization: Morphology Control and Spongelike Behavior

“…Droplet size and drop size distribution width were conserved within error through polymerization as verified by optical microscopy (Figure 6): for the emulsion with 40 wt% OEGMA, indeed the emulsion drop size before polymerization was 584 ± 176 µm and after polymerization 472 ± 114 µm. Interestingly, in previous studies performed by our group for similar polymerization systems within emulsions stabilized by surfactants, the obtained OEGMA/TEGDA latexes were only redispersible in aqueous medium, and not in the polymerization medium IPM, given the high hydrophilicity of the OEGMA/TEGDA polymer 25 .…”

“…The DSC thermograms are consistent with the polyethylene glycol entities present within the OEGMA, with a glass transition temperature (T g ) around -50 °C and a crystallization and fusion around respectively -7 °C and 5 °C34 . The loss of mobility of the pendant PEG chains with increasing cross-linker concentration caused the shift of the T g towards higher temperature values, and the disappearance of the crystallization and fusion peaks 25,34 . This observation is consistent with TGA analyses which show also a shift of the polymer degradation temperature towards higher temperature values with addition of the cross-linker (from 350 °C to 400 °C).…”

Encapsulation of Flavours and Fragrances into Polymeric Capsules and Cyclodextrins Inclusion Complexes: An Update

“…This strategy has the advantage of separating the polymerisation process, occurring in the aqueous phase that contains monomers, crosslinkers and an initiator, from the fragrance compartment. In this way, possible undesired reactions involving the fragrance during the polymerisation process are avoided [ 30 ].…”

Regulation Effects of Beeswax in the Intermediate Oil Phase on the Stability, Oral Sensation and Flavor Release Properties of Pickering Double Emulsions

“…Since the internal water phase can replace part of the oil phase, double emulsions exhibit potential in the development of low-fat foods [ 6 ]. In addition, the special two-membrane and three-phase compartmentalized structures in double emulsions impart an ability to delay the release of encapsulated functional ingredients and consequently to achieve a sustained or targeted release [ 7 , 8 ].…”