Solvent stable microcapsules for controlled release of actives
- Autores: Mario Ammendola
- Directores de la Tesis: Ricard Garcia Valls (dir. tes.), Raúl Rodrigo Gómez (codir. tes.)
- Lectura: En la Universitat Rovira i Virgili ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Marta Giamberini (presid.), Xavier Martínez-Lladó (secret.), Giuseppe Cesare Lama (voc.)
- Programa de doctorado: Programa de Doctorado en Nanociencia, Materiales e Ingeniería Química por la Universidad Rovira i Virgili
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
This thesis is focused on the production and characterization of polymeric microcapsules. Microcapsules are spherical particles with diameter between 1 µm and 1000 µm. They are constituted by a polymeric shell and a core material entrapped by the wall. The most common reasons for encapsulation are protection and control the release of the active. Microcapsules are applied in several fields, such as pharmaceutic, food, medicine, agriculture, cosmetics and textile, among others. Due to their multiple use, different microencapsulation techniques have been developed and the technology is in continuous progress due to big market impact of microcapsules.
In the present work, the main objective is the development of solvent stable microcapsules for controlled release of actives, to be included in consumer goods for personal and home care applications. The core material is a technical accord, called Sweet & Smart (S&S), that is a mix of fragrances with a high content of low logP perfume raw materials, that makes difficult its encapsulation. The encapsulation of S&S would make possible the enlargement of the palette of perfumes to be encapsulated and consequently a wider flexibility in the perfume formulations. The result is the possibility to provide different perfume characters, adducing commercial value to the consumer goods. Another important point of the work is sustainability of the system, because of modern societal trends aimed at finding more eco-friendly solutions.
Therefore, the first step of the work was the selection of the materials. Materials and encapsulation technique are not independent choice. We selected cellulose acetate (CA) as wall material and it was constant in all the work. CA meets our environmental considerations because it is a natural derived polymer and it has been found to be degradable; moreover, it passed the screening test that we performed. The second step was the exploration of the encapsulation technique and the study of process parameters. We started with processes based on atomization technology. First by spray drying, because of its easiness and because it is an economic and industrially available process. Then, we developed an encapsulation process, the vapor induced phase separation (VIPS) by implementing the immersion precipitation technique (IPS). IPS is a technique in which the polymeric solution containing solvents, polymer and core material is atomized by passing through a nozzle and the phase inversion precipitation is induced by immersion in liquid non-solvent. In VIPS, the phase separation is induced by non-solvent vapor, allowing a better control of the precipitation rate of the encapsulation material. The third technique is a solvent evaporation using Pickering emulsifier. Pickering emulsifier are solid particles that stabilize an emulsion instead of surfactants. The interest in this technique is growing because of the better stability of the emulsions and the possibility to avoid adverse effects of surfactants.
The prepared microcapsules were characterized through different techniques: SEM, Optical Microscopy, TGA, GC/MS, among others. The morphology of microcapsules for industrial applications is a crucial point, because perfume materials are quite expansive. A core-shell structure allows to optimize the amount of perfume contained in the capsules and their release. Therefore, the activity of the capsules, that is defined as the weight percentage of active encapsulated, and the encapsulation efficiency, defined as the mass of encapsulated active compared to the mass of the active added to the initial formulation, take on a very important value.
Finally, the performance of the microcapsules was evaluated in standard industrial test, such as the laundry machine test, to assess their potential application in full product formulations.
