Project Details Structure-based Nomenclature for Regular Linear, Star, Comb and Brush Polymers

Project No.:
2013-031-3-800
Start Date:
15 October 2013
End Date:
Division Name:
Chemical Nomenclature and Structure Representation
Division No.:
800

Objective

Between 1984 and 2012, IUPAC has published a set of recommendations for the nomenclature of a wide variety of polymer types such as regular linear single-strand, irregular single-strand, double-strand, regular single-strand organic polymers and quasi single-strand inorganic and coordination polymers, etc.  However, the nomenclature of certain types of branched polymers with three or more blocks of identical constitutional repeating units (CRU) (three-arm star, four-arm star or brush, etc.) has not yet been addressed by IUPAC.  This project will propose the recommendations for the nomenclature of polymer types of linear single-strand with two or more blocks of identical CRUs and branched (star, comb and brush-like), three or more blocks of identical CRUs with a central non-repeating junction unit.

Description

IUPAC has published structure-based nomenclature recommendations for irregular single-strand organic polymers and regular single-strand organic polymers in 1994 (Pure Appl. Chem., 66, 873-889 (1994); https://dx.doi.org/10.1351/pac199466040873) and 2002 (Pure Appl. Chem., 74, 1921-1956 (2002); https://dx.doi.org/10.1351/pac200274101921) respectively. In 1997, an IUPAC document on source-based nomenclature for non-linear macromolecules and macromolecular assemblies, in which some branched and star polymers were addressed, has also been published (Pure Appl. Chem., 69, 2511-2521 (1997); https://dx.doi.org/10.1351/pac199769122511). However, the systematic names for structure-based representations of star, comb and brush polymers are still inadequate and it is highly desirable to develop a nomenclature system for them.

In this project, new nomenclature guidelines will be proposed for some specific types of structure-based represented polymers, which contain identical constitutional units all connected identically with respect to a central moiety.

The first type of polymer is a linear, single-strand with two blocks of identical CRUs, depicted generically as EG1-(CRU)n-J-(CRU)n-EG2 in which EG1 and EG2 are end groups, CRU is a constitutional repeating unit, and J is a simple or complex non-repeating junction unit. Naming of these polymers depends upon several factors, such as whether J is symmetrical or asymmetrical, and whether the CRUs are in identical or non-identical environments, i.e., connected head-to-head, head-to-tail or tail-to-tail.

The second type of polymer is a linear, single-strand with more than two blocks of identical CRUs. It can be represented for example as EG1-(CRU)n-J-(CRU)n-J-(CRU)n-EG2, in which EG1 and EG2 are­­­ end groups, CRU is a constitutional repeating unit, and J is a simple or complex non-repeating junction unit. Naming of these polymers depends upon several factors, such as whether non-repeating junction units, J, which connect the CRU blocks are identical, whether the end groups are identical, and whether the CRUs are in identical or non-identical environments, i.e., connected head-to-head, head-to-tail or tail-to-tail.

The third type of polymer is a star type with three or more identical blocks of CRUs connected to a central non-repeating junction unit. It can be represented, for example, as

(CRU)n-EG

|

EG-(CRU)n-J-(CRU)n-EG

|

(CRU)n-EG

Naming of these polymers is more difficult than for the linear types of polymers, particularly if the end groups are not identical, the central non-repeating junction unit is branched in such a way that it is unnamable as a complete subunit, or the environment for each CRU is not identical. The general procedure for naming these polymers would be: to examine and identify the maximum number of CRUs in identical environments; treat as many occurrences as possible of CRUs in identical environments (with respect to head to tail orientation and connectivity to other subunits) as equal co-parents; designate the other CRU(s) as subordinate.

The fourth type of polymer is a multi-branched (comb-like) type with a backbone comprising several subunits, of which only one has a connectivity of three. It can be represented, for example, as

EG-(J-K-L-M…)n-EG

|

(CRU)n-EG

(in which J is the senior subunit of the CRU (J-K-L-M…))

or

EG-(H-I-J-K…)n-EG

|

(CRU)n-EG

(in which H is the senior subunit of the CRU (H-I-J-K…)).

In both examples, J represents the branching subunit and the other letters (H, I, K, L and M) represent non-branching subunits.

The general procedure for naming these polymers would be: regard the group -(CRU)n-EG as a substituent and moieties such as -(J-K-L-M…)n– or -(H-I-J-K…)n– as the main chain; name the polymer.

The fifth type of polymer is also a multi-branched (brush-like) type with a backbone comprising several subunits, of which only one has a connectivity of four. It can be represented, for example, as

(CRU)n-EG

|

EG-(J-K-L-M…)n-EG

|

(CRU)n-EG

(in which J is the senior subunit of the CRU (J-K-L-M…))

or

(CRU)n-EG

|

EG-(H-I-J-K…)n-EG

|

(CRU)n-EG

(in which H is the senior subunit of the CRU (H-I-J-K…)).

The general procedure for naming these polymers would be the same as naming type four polymers: regard the group -(CRU)n-EG as a substituent and moieties such as -(J-K-L-M…)n– or -(H-I-J-K…)n– as the main chain; name the polymer.

The nomenclature of irregular linear, star, comb and brush polymers with more than one type of CRU will be addressed in a future project.

Progress

May 2017 update – The project document has been revised many times in the past three years, and the current version of the document is version 8. Last year, the document was further modified after Istanbul meeting and task group members agreed that the version 8 document was ready to be reviewed inside of IUPAC. So, document version 8 was sent to SPT, Division IV and Division VIII members for review on December 2016. Comments and suggestions were collected in the early this year. Currently, we are working on the new version of the document to adopt the suggestions from IUPAC members. The plan is to further discuss the document in Sao Paulo meeting and finalize the document this year. Our goal is to submit the document for ICTNS review and publication by the end of this year or early next year.

Nov 2019 update – The outcome publication is being finalized and is under review with the Subcommittee on Polymer Terminology (SPT) for a second reading and prior to its final submission for publication in Pure and Applied Chemistry. A new project intended to complement this one has been approved and is titled “Structure-based nomenclature for irregular linear, star, comb and brush polymers with different types of constitutional repeating units (CRU)” (project 2019-036-1-800).

Last update: 27 Nov 2019