Environmentally friendly polymers are ones that readily break down though photochemical, biochemical or oxidation reaction pathways. Biodegradable polymers are ones which degrade through the action of microbial enzyme catalyzed reactions. There is considerable interest in biodegradable polymers for packaging and for a variety of medical applications such as bioabsorbable sutures, sustained drug delivery systems and a variety of orthopedic and plastic surgery implants. One of the most well known biodegradable, bioabsorbable polymers is polylactic acid. This polymer was first synthesized in the 1930s by the famous polymer chemist, Wallace Carothers. The structure of polylactic acid is given in the following figure.
The portion of the polymer that is most susceptible to attack by microbial enzymes is the ester linkage
Biodegradable polymers are unfortunately somewhat more expensive than many of the petrochemical based plastics used in food packaging. This price differential may narrow as petroleum prices increase and technological advances are made in the production of lactic acid from starch in through fermentation reactions.