Nomenclature and terminology for linear lactic acid-based polymers (IUPAC Recommendations 2019)

Vert, M., Chen, J., Hellwich, K., et al.

Pure and Applied Chemistry, 2020

Volume 92, Issue 1, pp. 193-211

For more than 60 years, scientists have studied polymers based on lactic acid enantiomers. This family includes aliphatic polyesters and linear, branched, and star copolymers containing lactic acid-based aliphatic polyester segments. These polymers have been developed primarily for applications in biological situations where full performance is required for only a limited period of time, after which degradation and elimination occur. Areas of application include surgery, pharmacology, regenerative medicine, dentistry, ecology, agriculture, packaging, etc. To take full advantage of the outstanding properties of these polymers, it is essential that a unique terminology and mode of naming is used to identify, qualify, and distinguish the members of this polymer family and their particularities.

Table 1

Structures and names of the lactic acids used for preparation of lactic acid-based polymers

1:1 mixture of R and S enantiomers (racemate)
Preferred IUPAC names (PINs)
(R)-2-hydroxypropanoic acid(S)-2-hydroxypropanoic acidrac-2-hydroxypropanoic acid
Other IUPAC approved names
(R)-lactic acid(S)-lactic acid(RS)-2-hydroxypropanoic acid

rac-lactic acid

(RS)-lactic acid

A polymer can be systematically named using either the ‘Structure-based’ or the ‘Source-based’ nomenclature systems extended to non-linear macromolecules. Both systems are general and enable the naming of most organic polymers. However, in the case of chiral aliphatic polymers based on lactic acid enantiomers, academic and patent literatures can be confusing, because specialists as well as non-specialists frequently use different names and abbreviations that do not respect the particularities originating from the source and structure-dependent factors affecting material and degradation properties. In order to facilitate an efficient exchange of accurate information, the IUPAC Subcommittee on Polymer Terminology prepared the present recommendations, which provide the nomenclature and terminology rules and the abbreviations to be respected in all fields concerned with the science and the applications of these degradable polymers.

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