Biopolymers

Biopolymers are polymers produced by living organisms or derived from renewable biological resources. They include natural polymers such as polysaccharides (cellulose, starch, chitosan, alginates), proteins (collagen, silk fibroin, elastin), and nucleic acids (DNA, RNA). Some biopolymers are accumulated by microorganisms as storage compounds, notably polyhydroxyalkanoates (PHAs). The properties and biodegradability of biopolymers vary with monomer composition, chain architecture, and crystallinity, influencing mechanical strength and thermal behavior.

Production and sources: extracted from biomass (plants, crustacean shells, microbial cells) or synthesized by fermentation and enzymatic processes. Some biopolymers are produced in situ by organisms, while others can be produced industrially via fermentation pathways or extraction from biomass. PHAs are produced by bacteria under nutrient imbalance; cellulose and starch are plant-derived.

Applications: packaging and films, food thickeners and stabilizers, pharmaceutical and medical uses (drug delivery, wound dressings), tissue engineering (scaffolds from collagen, alginate hydrogels), agriculture (soil conditioners). Biopolymers like chitosan have antimicrobial properties.

Environmental considerations: because many biopolymers are biodegradable and derived from renewable resources, they can reduce reliance on fossil-based plastics, but functionality and cost remain challenges; end-of-life behavior depends on composting or industrial composting facilities, as well as environmental conditions.

History and research: interest grew in late 20th century; ongoing work focuses on improving mechanical properties, processability, and production efficiency; development of nanocellulose and biopolymer blends.