BIOMATERIALS - Bioengineering for Pollution Prevention - page 47

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B. P OLYLACTIDES
1. Introduction
The family of bioplastics known as PLA encompasses the set of polymers of lactide, a
cyclic dimer produced by the dehydration of lactic acid, which represents a highly promising
and versatile category of biomaterials. The development of PLA into a commodity polymer
has spanned over six decades of research and design from inception to the present commercial
utility. The recorded history of PLA development began in 1932 when Carothers and
colleagues documented the earliest attempted polymerization and depolymerization of
oligomeric lactides in the Journal of the American Chemical Society [1]. In 1954, the DuPont
Corporation synthesized high molecular-weight PLA with improved lactide purification
techniques, as well as antimony trioxide and antimony trihalide as polymerization catalysts
[2]. Later, methods were developed to produce high molecular weight PLA with properties
sufficient for competition with traditional oil-derived polymers. Higher molecular-weight
PLA was found to have interesting properties, but its production was prohibitively expensive.
In the 1960s, several researchers investigated relationships between the chemical structures of
lactide monomers and the configurations and crystalline structures of resulting PLAs [3-7].
Because of its inherent biodegradability, PLA was one of the earliest polymers used in
biomedical applications; Kulkarni et al. demonstrated the human body's ability to absorb
PLA-based sutures in 1966 [8]. Work in the 1970s and 1980s focused primarily on discovery