Desenvolvimento e caracterização de filmes de celulose bacteriana modificados com MXene para aplicações em embalagens de alimentos

Abstract

Bacterial cellulose (BC) is a polysaccharide that has gained prominence in the development of food packaging materials, helping to reduce dependence on fossil-based materials. Among the various desirable characteristics for such applications are its non-toxicity, biodegradability, potential to be obtained with a high degree of purity, and its three-dimensional nanofibrillar structure, which provides a high surface area and excellent mechanical properties. In this study, BC membranes were modified through impregnation with MXene (titanium carbide Ti₃C₂Tₓ) in order to improve properties such as tensile strength, hydrophobicity, and water permeability, as well as to confer antioxidant activity and ultraviolet (UV) radiation shielding. MXenes are two-dimensional (2D) materials in which layers composed of a transition metal are intercalated with carbon and/or nitrogen layers. These nanomaterials stand out due to their high electrical conductivity, large surface area, surface functional groups, and excellent interaction capability with polymeric matrices. The effect of MXene was evaluated both in the presence and absence of a plasticizer (glycerol), varying the number of membrane immersions in aqueous dispersions. The obtained films were characterized regarding their morphology and their mechanical, optical, and chemical properties. After MXene incorporation, an increase in UV radiation blocking was observed, exceeding 80% in the UVA region and 90% in the UVB and UVC ranges. Furthermore, the use of MXene also resulted in enhanced antioxidant activity and electrical conductivity. Scanning electron microscopy images suggested that MXene incorporation occurred mainly on the surface of the BC membrane, explaining the less significant changes observed in the other analyzed properties. The addition of the plasticizer resulted in a more flexible and translucent material. However, the presence of glycerol made BC more permeable to water, less opaque, and less resistant to high temperatures. Regarding mechanical resistance, the presence of glycerol reduced the tensile strength limit and increased the elongation at break of the membranes. Improvements in tensile and mechanical properties were also observed after MXene incorporation, with a maximum increase in the elastic modulus of approximately 570%.