Over the past few centuries, plastics have developed rapidly because of their low cost, corrosion resistance, lightness and conveniences. Most plastic packaging is synthesized from petroleum-based polymers and creates significant waste disposal challenges owing to its non-degradability and non-recyclability (Pasaoglu and Koyuncu, 2021). As reported, 430 million tons of plastic are consumed and then incinerated, buried, etc. (Liu et al., 2018), every year. It results in severe groundwater pollution, marine microplastics hazard, and carbon emissions, posing a hostile threat to the global ecology and human health (Payton et al., 2020; Wang et al., 2020b). Consequently, exploiting biodegradable and sustainable packaging materials to replace the traditional plastics has been an imperative task. Natural polysaccharides such as cellulose (Yun et al., 2023), starch, and chitin are most commonly used to prepare wrappers because of their abundance, cost-effectiveness, biodegradability, and nontoxicity.
Cellulose is the most abundant natural polymer on earth, consisting of glucose units linked by β-(1–4) glycosidic bonds. It can be synthesized into multifunctional biodegradable materials through physical or chemical modification, making it useful in cellulose-based packaging materials and other fields. Cellulose-based packaging materials are classified into several types, including film (Bourakadi et al., 2019), aerogel, paper (Li et al., 2017) and other types. The preparation methods are mainly spray method (Li et al., 2024), solvent casting method (Wen et al., 2018), and layer-by-layer self-assembly method. Nanocellulose has become an ideal material in the field of green food packaging own to its large specific surface area, good mechanical properties, excellent biocompatibility, non-toxicity and degradability. In food packaging, antibacterial ability is a key indicator of the degree of excellence of packaging materials, in addition to mechanical and barrier properties. The poor compatibility of packaging materials and antimicrobials might lead to the transfer of antimicrobials to food, which is a safety hazard. To avoid this hazard, it was important that packaging materials and antimicrobials be compatible. Cellulose and chitosan are structurally similar and compatible. Meanwhile, chitosan (CS) is an abundant and fascinating polymer found in nature, often referred to as the 'sixth element of life'. Due to the antibacterial, hypotensive, anti-tumor, and immunomodulatory properties (Jamshidifard et al., 2019), CS is used in the fields of food antimicrobial, textile industry and healthcare. Additionally, it exhibits exceptional film-forming properties, making it a suitable material for use in the food and packaging industries (Tripathi et al., 2009). Surface modification of cellulose-based packaging materials with antimicrobial properties has a promising future in the fields of food packaging, medical, and hygiene.
In recent years, superhydrophobic surfaces have rapidly developed and provided novel ideas for designing and preparing functional food packaging materials. As a multifunctional, efficient, and smart surface, superhydrophobic showed promising application prospect in the fields of self-cleaning, anti-bacterial adhesion, and liquid food packaging (Wang et al., 2020a; Yu et al., 2023). Superhydrophobic surfaces were initially inspired by natural flora and fauna, such as lotus leaves, roses, and water striders. Further research had shown that the low surface energy or micro/nano structure of the material surface induced super-hydrophobicity. So far, various methods have been used to create superhydrophobic packaging materials, including chemical grafting, atom transfer radical polymerization (Wu et al., 2018), and rapid supercritical CO2 (Werner et al., 2009). Nevertheless, these methods had been limited by expensive instrumentation, insufficient material durability, and poor adhesion of the superhydrophobic coating to the substrate, which has hindered their large-scale application. To tackle these issues, a straightforward and feasible low-surface-energy material strategy is proposed. Natural waxes, such as white beeswax (BW) and carnauba wax (CW), were ideal for creating superhydrophobic materials due to their low surface energy. CW was particularly advantageous owing to its low cost, high melting point, good gloss, moisture resistance, and oxidation resistance, making it a popular choice in the superhydrophobic materials industry (Susmita Devi et al., 2022). Wang et al. reported that polylactic acid (PLA) and CW were prepared into biodegradable superhydrophobic PLA/CW coatings using a spraying technique (Wang et al., 2023). In contrast to the complex preparation methods and difficult degradation of traditional superhydrophobic materials, the PLA/CW coatings exhibit excellent super-hydrophobicity and heat resistance. In addition, they could be used for self-cleaning and oil-water separation applications. Accordingly, the study of superhydrophobic materials and coatings using these degradable, low-cost, and abundant feedstocks under limited scale conditions still has considerable promise for the future.
Despite the numerous research studies conducted on cellulose-based packaging materials, there are still issues with complicated preparation methods, poor performance, and multiple properties that are incapable of integration. Therefore, we herein the layer-by-layer self-assembly technique was adopted to prepare cellulose-based superhydrophobic packaging materials via self-assembly of positively and negatively charged layers, followed by low surface energy modification. The material exhibited remarkable mechanical properties and abrasion resistance. Additionally, it demonstrated good anti-adhesion, durability, and antibacterial properties. This work presented a novel avenue for research in superhydrophobic coatings, cellulose-based flexible electronics, paper industry, packaging materials, and medical treatment.