Increasing the Deposition Efficiency of Perfume Ingredients in Liquid Detergents

The aim of this project is the development of perfume stabilization technologies for use in liquid detergents, which represent very complex mixtures of natural and synthetic molecules. Current fragrance carriers (mainly polyacrylate-, poly-vinyl alcohol- or polystyrene- based polymer capsules) present a good compatibility with the laundry detergent components and a high perfume loading efficiency. However, the main drawback of this technology is the perfume leakage, that is caused by the breakage of the rigid capsule wall, due to mechanical stress. Once the capsule is broken the fragrances leak out, are emulsified by the surfactants contained in the detergent matrix and finally are washed off. As a consequence, a high amount of technology is required in order to achieve the benefit for the consumers. On these bases, our aim is the design of innovative perfume carriers with i) excellent stability in liquid detergent formulation and ii) improved deposition during product application. Among the possible candidates for the development of such a technology, vinyl alcohol-based copolymers, currently referred to as PVA (poly vinyl alcohol) or EVOH (poly ethylene-co-vinyl alcohol), represent a suitable tool to obtain a carrier system which can be used for the purpose of this project thanks to the great stability of their aggregates in water, their biocompatibility and biodegradability. Moreover, particles formed by these copolymers are characterized by excellent transport properties: indeed, diverse vinyl alcohol-based systems have been already proposed as carriers in biomedical applications or environmental science for pollutant removal. An efficient procedure to obtain PVA or EVOH-based particles consists of promoting the aggregation of the chains by preparing a polymer solution and adding a certain quantity of a salt (i.e. NaCl) that is able to favor the salting-out process: this effect was already tested for different water soluble polymers. In order to achieve the purpose of this project, we focused on: i) Characterization of the aggregation process; ii) Study on the structural properties of polymer aggregates prepared through the salting-out effect; iii) Investigation about the interaction among polymers and two common surfactants used in the final formulation; iv) Study on the fragrance segregation process; and v) Evaluation of the technology efficiency through washing tests.