**2. Biopolymers vs. Conventional Synthetic Materials**

Several studies have been conducted concerning the utilization of biopolymers with the aim of developing sustainable packaging materials. Although significant improvements have been made, there is still considerable debate over economic considerations, environmental concerns, and product packaging performance [31].

Living organisms produce a variety of polymers as a significant part of their morphological, cellular, and dry matter. These biopolymers play vital roles in the life cycle of organisms including the preservation and expression of genetic information, catalysis of reaction [32], energy or other nutrients, sensing of abiotic and biotic factors, protecting against the attack of other cells, storage of carbon, and negotiation of the adhesion to the surface of other organisms [4].

Biopolymers present important features such as biodegradability [33,34], biocompatibility [35], sustainability [36], bioresorbability [37], flexibility [38], antibacterial activity [6], renewability [39], and stability [2]. They are also less toxic [40], non-immunogenic [41], non-carcinogenic, non-thrombogenic, carbon neutral, and have the advantage of easy extraction [42]. These properties are directly influenced by parameters such as the type of material used as the structural matrix (charge distribution, molecular mass, and conformation), film developing conditions (concentration, pH, solvent, temperature, etc.) and category and concentration of additives (antimicrobials, crosslinking agents, plasticizers, antioxidants, etc.) [43].

Until recently, conventional synthetic materials have become part of most materials in our lives, including those present in beverages and food, clothes, daily used instruments, and baby-toys, and even in biomedical applications such as surgical equipment, drug delivery systems, and cosmetic personal care materials. Some studies have associated these materials with potential adverse health problems, particularly in pregnant women and newborn infants. To this end, hormonally active agents are a group of polymeric chemicals that have been associated with critical health issues such as cancerous tumors, congenital disabilities, and other disorders [40]. Furthermore, people have become more aware of the effects of chemically derived compounds and are more cautious in their use of conventional synthetic materials due to their effects on health and the environment. Today's consumers are more informed and sophisticated in their preferences and choices, increasingly looking for natural and vegan alternate products with high biocompatibility and low environmental implications. Furthermore, increasing efforts and research on the management of plastic waste on Earth are aimed towards finding eco-friendly alternatives to plastics [5]. Such eco-friendly alternatives can be represented by biopolymers, which are disposed in the environment and easily degradable through the enzymatic actions of microorganisms [44].

Compared with conventional synthetic materials that have a simpler and more random structure, these biopolymers are complex molecular assemblies that adopt defined and precise 3D configuration and structures [45]. Based on the composition and chemical structure of biopolymers, they are almost identical to the macromolecules of the native extracellular environment [46]. Many characteristics differentiate between the two types of materials, which are summarized in Table 1. Biopolymers have multiple advantages over conventional plastics due to their low/no toxicity, biodegradability, sustainability, biocompatibility, and extreme hydrophilicity. Furthermore, their morphology and chemical modifications can have a significant impact on their rate of biodegradation [47], an important feature in the development of new applications for food, biomedical, and pharmaceutical industries. Conversely, synthetic materials have a low cost and high thermal and mechanical properties that make them more usable than biopolymers.

Some applications of biopolymers have used mixtures with synthetic materials (such as polyethylene and polyvinyl alcohol), plasticizers (sorbitol and glycerin), nitrogenous bases, and others, thus obtaining a partially biodegradable material [7].


**Table 1.** Characteristics of biopolymers vs. synthetic polymers.

Although biopolymers have many advantages, there are a number of limitations in their processing, starting from the extraction and all the way up to the final product. First, being a completely natural product, biopolymers' final properties depend largely on the raw material. This can vary greatly due to the origin, climatic conditions, location, harvesting, and processing. Therefore, the world production of biopolymers cannot always maintain the same sustainability. To date, no universal acceptable procedures have been developed for the collection and manufacturing of biopolymer powders from vegetable materials. This is important both for the safety as well as the quality and performance of the final product. Second, because the production of biopolymers is still in its infancy, the production costs are quite high [55]. However, the elimination of recycling and waste taxes through world legislation mitigates some of the high costs. Third, the production of biopolymers necessitates special equipment other than those currently used. The development of such equipment and protocols requires time, additional costs, and trained staff. However, given that biopolymer processing technology is relatively easy and accessible, some existing equipment has been adapted for this purpose, thus reducing the costs [56]. Finally, the lower performance of biopolymers compared to conventional materials may limit their use, although continuous research advances in the technology and material combinations show great improvements in their characteristics that are comparable to conventional materials currently used [57].
