This study aims to develop new bio-based materials for food packaging using air spraying as a cost-effective manufacturing method. Materials prepared in the form of films were based on cellulose acetate (CA) modified with chitosan (CS), both purchased from Sigma Aldrich, St. Louis, MO, USA. The morphology, structure and performance in terms of thermal, mechanical, wettability and antibacterial behaviour were studied considering two variables: the solvent used to prepare solutions to be sprayed, acetic acid (HAc) or formic acid (FA) and the composition of the polymer system, 0%, 2.5%, 5% and 7.5% by CS weight. The resulting CA/CS composite films obtained exhibited remarkable flexibility and mechanical strength despite being derived from rigid, high-molecular-weight biopolymers. This flexibility is attributed to the unique droplet-based morphology of the films. Increased chitosan content led to enhanced surface roughness and higher water and oil contact angles, indicating improved hydrophobicity. Notably, films with 7.5% chitosan demonstrated antibacterial activity against E. coli, showing inhibited colony growth compared to pure CA films. Therefore, with this study it has been demonstrated that air spraying enables the fabrication of flexible, mechanically robust, and bioactive CA/CS films without the need for plasticizers. Their unique droplet-based morphology, high water contact angle, and antibacterial activity against E. coli highlight their suitability for sustainable food packaging. The use of biopolymers and an efficient processing method positions this approach as a promising alternative to conventional film-forming techniques.
Author Contributions
Conceptualization, A.K. and J.G.-B.; methodology, N.M.F., A.K. and J.G.-B.; validation, N.M.F., A.K. and J.G.-B.; formal analysis, N.M.F., A.K. and J.G.-B.; investigation, N.M.F., A.K. and J.G.-B.; resources, A.K. and J.G.-B.; data curation, N.M.F., A.K. and J.G.-B.; writing—original draft preparation, N.M.F.; writing—review and editing, A.K. and J.G.-B.; visualization, N.M.F., A.K. and J.G.-B.; supervision, A.K. and J.G.-B.; project administration, A.K. and J.G.-B.; funding acquisition, A.K. and J.G.-B. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by CONEX-Plus program of Universidad Carlos III de Madrid (UC3M) and the European Commission through the Marie-Sklodowska Curie COFUND Action, grant number 801538, by the Ministerio de Ciencia, Innovación y Universidades of Spain (MICIU/AEI/10.13039/501100011033, Project I + D + i PID2020-112713RB-C22), and by the University Carlos III de Madrid, Fondos de Investigación of Fco. Javier González Benito, grant number 2012/00130/004, and the strategic Action in Multifunctional Nanocomposite Materials, grant number 2011/00287/003.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
The raw data supporting the conclusions of this article will be made available by the authors on request.
Conflicts of Interest
The authors declare no conflicts of interest.
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