# Recent Developments in Materials Science for the Conservation and Restoration of Historic Artifacts
## 5 Biopolymers: Sustainable Conservation Solutions
### Properties and Advantages of Biopolymers  
Biopolymers are naturally occurring polymers derived from renewable biological resources, offering several advantages over traditional synthetic polymers, making them particularly suitable for use in conservation.  
One of the most significant advantages of biopolymers is their biocompatibility. This property allows them to interact favorably with biological systems without causing adverse effects. In conservation, this means that biopolymers can be used on sensitive materials without risking damage or degradation [77]. Biopolymers also typically exhibit low toxicity levels compared to synthetic alternatives, an aspect particularly important in conservation contexts where the health and safety of conservators and the integrity of artifacts must be prioritized [78]. The low toxicity of biopolymers makes them suitable for use in environments where human exposure is possible.  
Biopolymers are also biodegradable, meaning they can break down naturally over time into non-toxic byproducts, a property that significantly reduces the environmental impact associated with their disposal [79]. In contrast, synthetic polymers often contribute to long-term pollution due to their resistance to degradation. This biodegradation process of biopolymers involves microbial action, which leads to a return to natural cycles without leaving harmful residues [80]. This characteristic aligns with contemporary sustainability goals in conservation practices. By utilizing biodegradable materials, conservators can mitigate the ecological footprint of restoration efforts.  
Regarding their mechanical properties, many biopolymers exhibit favorable mechanical properties, including strength and flexibility. For example, chitosan--a biopolymer derived from chitin--has been shown to possess excellent tensile strength and elasticity, making it suitable for various applications in conservation [81]. The mechanical properties of biopolymers can be tailored through chemical modifications to meet specific requirements. Other biopolymers such as gelatin and alginate can form films that are useful for protective coatings. These films can provide a barrier against environmental factors while allowing for gas exchange, which is essential for maintaining the integrity of certain materials [82]. The ability to form films also allows for easy application on various substrates.  
In terms of customizability, the chemical composition of biopolymers can be modified to achieve specific properties or functionalities. This versatility allows conservators to develop formulations that meet the unique requirements of different artifacts [83]. For instance, the addition of plasticizers can enhance flexibility while maintaining mechanical strength. Biopolymers can also be functionalized with various agents to impart additional properties such as antimicrobial activity or UV resistance. This capability expands their potential applications in conservation [84]. Functionalized biopolymers can provide multiple benefits within a single formulation.