Novos Solventes Eutéticos Profundos baseados no núcleo benzalcônio e sua aplicação na formulação de filmes biodegradáveis.

Abstract

The interest in the use of sustainable materials in the production of biodegradable packaging has grown lately. Starch is a very advantageous biopolymer for application in the formulation of biodegradable films, being totally sustainable, low cost, abundant in nature, easily dissolved in water, and presents a thermoplastic behavior. However, the films formed are very soluble in water and have very weak mechanical properties. Thus, the addition of plasticizers to the polymeric matrix gives the film better mechanical properties. Glycerol is the most widely used plasticizer today, but its efficiency has been contested due to its strong influence on the recrystallization of starch during storage, resulting in a brittle material. Therefore, it is necessary to add other agents with technical features similar to conventional plasticizers and that improve the physical-chemical properties of biofilms, so that these features are comparable to the conventional plastics. In this way, Deep Eutectic Solvents (DES) emerged as a promising alternative to be applied as solvents and/or plasticizers, aiming not only to improve the mechanical properties of the film, but also the possibility of adding a secondary function, such as antimicrobials, preservatives, antiseptics, among others. Thus, the objective of this work was to synthesize new DES derived from benzalkonium chloride and organic acids ([BzkCl:AcCit], [BzkCl:AcOx] and [BzkCl:Gly]) and evaluate their efficiency as additives in the formulation of films biodegradable starch based products. The characterization of the new compounds was carried out using infrared and ionic conductivity spectra. The change in acidity and ionicity levels of film-forming solutions, resulting from the addition of DES, was also evaluated. Biodegradable films were characterized by analysis of physical-chemical, optical and water affinity properties, using as a standard for comparison the film made with glycerol (1%). The formulation with 0.5% of DES [BzkCl:AcCit], derived from citric acid, showed the best results in terms of opacity, being 42% more transparent than the standard film. In addition, the results for the percentages of humidity and solubility were 30% lower and 67% higher, respectively. As for water vapor permeability, despite not having the best result, its values were lower than those of the glycerol standard. The data obtained in this work demonstrated the efficiency of benzalkonium chloride for the formation of new DES and its use as functional additives for starch-based biodegradable films, resulting in better optical and physical-chemical properties, when compared to the standard film.