Polymer Reactant and SRU Naming Conventions

Most polymers are represented on the Inventory in terms of the starting materials from which they are manufactured. More than 80% of the polymers on the TSCA Inventory are listed in terms of starting materials. 

2-Propenoic acid, polymer with 2,2 -azobis[2-methylpropanenitrile] and butyl 2-propenoate (CASRN 68083-62-5) 

For TSCA purposes, SRU names are used only for several types of common polymer backbones in which the structure of the polymer is known or reasonably ascertained to consist of repeating units instead of being random, and where there is a reported average number of SRU, a variable range of SRU, or an unknown number of SRU. Polymers identified with SRU names on the Inventory include certain polyethylene glycols and derivatives, certain polypropylene glycols and their derivatives, and siloxanes and silicones. 

For a given polymeric substance represented by an SRU, the repeating part of the molecular formula is enclosed in parentheses with a subscript n. The n value in the molecular formula can represent (1) an unknown value, (2) a variable range, (3) an average value, or (4) a specific integral value of at least 11. There is no lower or upper limit to the average number or range of n to apply SRU nomenclature. An example of a simple SRU polymer is  

Poly(oxy-l,4-butanediyl), a-hydro-co-hydroxy-, CASRN 25190-06-1 (C4Hg0) H20 

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