Tuning the Encapsulation of Simple Fragrances with an Amphiphilic Graft Copolymer

The encapsulation of poorly water-soluble compounds such as perfumes, flavors, and bioactive molecules is a key step in the formulation of a large variety of consumer products in the fields of household care and personal care. We study the encapsulation ability of an amphiphilic poly(ethylene glycol)-graft-poly(vinyl acetate) (PEG-g-PVAc) graft copolymer, extending the focus to the entire phase diagram of polymer/perfume/water systems with three common natural fragrances. The three perfume molecules (2-phenyl ethanol, L-carvone, and α-pinene) possess different water affinities, as expressed by their octanol/water partition coefficients. The investigation of the polymorphism of PEG-g-PVAc in these systems is carried out by means of dynamic light scattering, small-angle X-ray scattering, NMR spectroscopy, and confocal laser scanning microscopy. The results presented here demonstrate that the choice of fragrance can dramatically affect the supramolecular structures formed by the polymer in aqueous solution, with important consequences on formulations of industrial interest such as the demixing of complex perfume blends when one or more of the components have no chemical affinity for any of the polymer blocks.