As challenges related to environmental protection and the depletion of fossil fuels become increasingly severe, some traditional non-degradable polymers will be replaced by biodegradable polymers. Among biodegradable polymers, polylactic acid (PLA) is one of the most promising biopolymers. Lactic acid (2-hydroxypropanoic acid, LA) is a component of PLA, and because it is a chiral molecule, it exists in two enantiomeric forms: L-lactic acid and D-lactic acid. PLA has stereoisomers, such as poly-L-lactic acid (PLLA), poly-D-lactic acid (PDLA), and racemic polylactic acid (PDLLA).
The structure of L-lactic acid and D-lactic acid
Advantages of polylactic acid
Compared to other biopolymers, the production of polylactic acid (PLA) has many advantages, including:
- Environmental friendliness. In addition to being produced from traditional fossil fuel-based products, PLA can also be synthesized from renewable resources such as corn, wheat, or rice. Furthermore, PLA is biodegradable, recyclable, and compostable.
- Biocompatibility. When PLA is implanted in biological organisms, including the human body, it hydrolyzes into its constituent α-hydroxy acids, which are then incorporated into the tricarboxylic acid cycle and excreted from the body. Additionally, the degradation products of PLA are non-toxic (at lower concentrations).
- Processability. Compared to other biopolymers such as polyhydroxyalkanoates (PHA), polyethylene glycol (PEG), and polycaprolactone (PCL), PLA has better thermal processability. It can be processed using techniques such as injection molding, film extrusion, blow molding, thermoforming, fiber spinning, and film formation.
Application of polylactic acid
Polylactic acid (PLA) is the first commercially produced polymer derived from renewable resources. It is classified as Generally Recognized as Safe (GRAS) by the U.S. Food and Drug Administration (FDA). Due to its biodegradability, biocompatibility, ease of processing, and other properties similar to traditional fossil-based polymers, PLA is widely used in the medical field, including applications such as surgical sutures, orthopedic fixation materials, tissue engineering scaffolds, and drug delivery systems. Additionally, it is extensively used in furniture textiles, packaging, composite materials, plastic films, and 3D printing.
various kinds of polylactic acid products