Post-Polymerisation Treatment and Devolvement

The post-reaction of a polymer with a chemical substance may result in the formation of a new polymer in which the chemical substance becomes chemically attached to the pre-polymer. In other instances, the post-reactant may not become part of a polymer chain because its role is not to continue propagation of a polymer, but rather to introduce a specific functionality to it. In these cases, it is not appropriate to include the substance as a reactant in the naming of the polymer. For example, when a hydroxyl-terminated polymeric diol is post-reacted with an acid, ester groups are formed which become end-groups of the original pre-polymer. In this case, the term polymer with the acid is not the most appropriate representation. The terms esters with the acid or reaction products with the acid are more appropriate. 

In practice, the naming of a new polymeric substance based on the post-reaction of a pre-polymer is best left to CAS. Although the rationale used by the EPA to name certain complex substances is often obscure, the EPA accepts the name that CAS assign in most cases and, if it does not, the regulated party (e.g., a PMN submitter) is not directly penalised through delays in EPA response. 

A complex example of CAS naming conventions involves its naming of two different, but nearly identical, post-reacted polymers. In both cases, the new substance was named as those monomers from the devolved pre-polymer, polymers with the new monomer(s). For example, suppose that a polymer of A, B, C, and D is post-reacted with monomers D, E, and F. Using the devolvement principle, this polymer may be named A, polymer with B, C, D, E, and E and it was so named by CAS. In a second case, in which a new monomer G was used, the name assigned by CAS was G, polymer with A-B-G-D, polymer with D, E, and F. Identity of the pre-polymer (polymer of A, 

and D) was therefore acknowledged through use of dashes, and monomer D appears twice because it is present in the pre-polymer and as a post-reactant. The rationale of CAS for naming a substance in this fashion may not be obvious, but it is based on its internal guidelines for naming substances. 

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