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Percorrer por autor "Domingos, Giovanna Martins"

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  • Development of multifunctional emulsions based on lignin and cellulose for cosmetic application
    Publication . Domingos, Giovanna Martins; Barreiro, Filomena; Sipoli, Caroline Casagrande
    The growing consumer demand for safer, more natural, and environmentally sustainable cosmetic products has driven the development of alternative formulation strategies. One promising approach involves emulsion systems stabilized by solid particles, rather than molecular surfactants, known as Pickering emulsions. These systems offer improved biocompatibility, enhanced stability, and eco-friendly character. Microcrystalline cellulose (MCC) containing residual lignin is an innovative material that has attracted industrial interest for high-value-added applications. In this context, the present work investigated the use of MCC at different lignin contents as a stabilizing agent in the development of multifunctional Pickering emulsions for cosmetic applications. The influence of lignin content on particle wettability and interfacial behavior was evaluated, as well as the effect of physical modification through high-pressure homogenization (HPH) and lignin particle precipitation within MCC samples. The MCC properties, including size distribution and wettability, were analyzed to correlate structural characteristics with emulsion performance. HPH modified the MCC structure and size, improving its dispersion behavior and Pickering-stabilizing performance. However, the processed samples also exhibited greater heterogeneity, and the significant increase in average particle diameter observed suggests the formation of fibrillar structures, particle aggregation, and/or re-agglomeration after processing. Pickering emulsions were successfully produced using MCC dispersions and Miglyol 812 as the oil phase under a 1:1 oil-to-water volume ratio. The resulting systems were characterized in terms of morphology, droplet size, emulsified layer formation, rheological behavior, and storage stability over time. The results showed that lignin content is a critical parameter governing the performance of MCC-based Pickering stabilizers, with small variations in residual lignin content significantly influencing particle hydrophobicity and emulsion stabilization efficiency. MCC Crude (18.7%) showed the highest stabilizing performance, indicating that the higher residual lignin content favored particle hydrophobicity and interfacial adsorption. In contrast, MCC White (4.0%) exhibited poor stabilization due to its highly hydrophilic nature, even after processing. MCC Blond (6.5%) provided intermediate stability while producing light-colored emulsions, a particular advantage for cosmetic applications. For the MCC Crude sample, the lignin particle precipitation approach altered the interfacial properties of the material; however, the results indicated that HPH processing was more advantageous for improving Pickering stabilization performance. Overall, this work demonstrated the innovative use of MCC samples containing residual lignin as Pickering stabilizers, advancing understanding of, and strategies to improve, their interfacial properties and stabilization mechanisms in high-value Pickering emulsions.
    2026Dissertação de mestrado Acesso embargado Ver mais