Lactic acid-based polymers are gaining a particular place in the field of new polymers that are of interest with respect to: i) desired degradability, ii) the concepts of renewable resources and sustainability (lactic acid is produced from natural products and biochemically processed back to natural products), iii) versatility related to outstanding possibilities for diversification of the backbone through stereocopolymerization, copolymerization or both. The aim of this project is to distinguish clearly: the various polymerization routes; the resultant macromolecular structures; the influence of chain ends known to play an important role in polymer degradation; and the effects of impurities on structure-property relationships via terminology.
The first stage of the project will be aimed at bringing the group members to a common level of familiarity and agreement as to the subtleties of the synthesis and the structural and degradative properties of these special polymers.
From thereon, a first list of terms to be precisely defined will be generated. At the first annual meeting of the Subcommittee on Polymer Terminology (SPT) after the project has started, a first draft of definitions will be submitted by the task group for general discussion, comments and criticisms from less informed people as a means to check that the suggested definitions are clear, understandable and profitable to the reader in distinguishing the differences between the full range of polymeric compounds often referred to as polylactide or poly(lactic acid) and abbreviated as PLA.
The document will be improved via successive exchanges between the task group members and between SPT members. When a comprehensive draft is completed, it will be submitted to selected potential users as approved by SPT for evaluation of its clarity and impact on future beneficiaries. The finalized document will be submitted for publication in PAC.
The work will be conducted in full consultation with existing task groups handling more general projects on stereochemistry and on abbreviations of polymer names.
October 2014 update – As initially planned, the first stage of the project consisted of the analysis of all the structural, morphological and degradation-related characteristics that make chiral lactic acid-based polymers and stereoregular copolymers exceptional in the science of artificial polymers. First, the collected information was organized to form a tutorial introduction, which was thought to be necessary because of the complex characteristics of lactic acid-based polymers, which are not systematically taken into account in the current literature.
In the second stage of the project, lists of chiral lactic acid-based monomers and of the corresponding chiral polymers and stereoregular copolymers have been compiled. The lists include traditional names currently used in the literature together with the corresponding IUPAC source-based and structure-based names. These names must now be elaborated to indicate secondary characteristics like the enantiomeric composition, distribution of the chiral units along the chains, degradation-related end group changes, informative abbreviations, etcâ€¦ to be used whenever these characteristics are being discussed.
The Task Group has also started to select some of the terms defined in the general “Terminology for Biorelated Polymers” IUPAC recommendations published in PAC in 2012 (Vol. 84, No. 2, pp. 377-410; https://dx.doi.org/10.1351/PAC-REC-10-12-04) in order to compare them with the particularities of lactic acid-based polymers and to emphasize these particularities by complementary notes.
May 2016 update – The advances were used to elaborate several drafts. Difficulties appeared when the group tried to combine IUPAC source-based and structure-based polymer rules of nomenclature with characteristics such as the enantiomeric composition, distribution of the chiral units along the chains, degradation-related end-group changes, informative abbreviations, etc. The IUPAC Congress in Busan (Aug 2015) was an opportunity to discuss a new draft and take decisions about the content and the limits of the final document. After several post-meeting on-line exchanges Draft 6 was elaborated to be discussed and finalised at the Istanbul meeting in July 2016 prior to submission to the SPT sub-committee for approval.
October 2017 update – A manuscript has been submitted to PAC and the publication of the recommendations can be expected in 2018.
January 2019 update – The provisional recommendations titled “Nomenclature and terminology for lactic acid-based polymers” is available for public review till 31 May 2019.
January 2020 update – The IUPAC recommendations are published in Pure and Applied Chemistry, 92(1), pp. 193-211, 2020; https://doi.org/10.1515/pac-2017-1007
Page last updated 17 January 2020