bChemical Abstracts Service, P.O. Box 3012, Columbus, OH 43210-0012

It will be the objective of this review to improve communication links to the IUPAC Commission on Macromolecular Nomenclature, and to summarize material suitable for consulting by the authors contributing to the POLY and PMSE Reprints. Thus, a number of examples will be given, with the corresponding IUPAC or related nomenclature references.

What many people call nomenclature in polymer science and engineering can be conveniently divided into two subcategories, nomenclature proper, and terminology. For example, the names such as polystyrene, polyamide 66, which are source-based, and the more formal IUPAC structure-based names such as poly(1-phenylethylene) and poly(iminohexamethyleneiminoadipoyl) are properly in the field of nomenclature, while names such as craze, fibril, modulus, interphase, and viscosity fall into the category of terminology. Up until now, the field of nomenclanure proper has been extremely active with numerous publications, while the field of polymer terminology, unfortunately, is just beguining to be systematically developed. The intent, overall, for both macromolecular nomenclature and terminology, is to provide a unique and easily understood name for every possible noun and verb utilized by polymer scientists and engineers. While the fields of organic and inorganic chemistry, through their longer history, have a well- organized and preeminently used nomenclature, one can still find in the modern polymer literature names for

such as polyvinyl chloride, polyvinylchloride, and worse, while the correct source-based name is poly(vinyl chloride). If this article encourages the reader to "look it up", then it will have succeeded!

While the history of macromolecular nomenclature stretches back to 1952¹ and beyond, the first modern report was published in 1968.² The names of a few common and uncommon polymers, derived from Ref. 2, are shown in Table 1. While the structures in the first row have both common and structure-based names, the ladder and heterocyclic ring system polymers in the next row only have structure-based names.

The recommendations in Ref. 2, limited to regular single-strand polymers, were adopted by the IUPAC Commission on Macromolecular Nomenclature.³ This was followed by a significant number of papers on other polymers including multicomponent polymers such as block copolymers,⁴ inorganic polymers,⁵ double-strand polyrners,⁶ irregular organic polymers,⁷ and more recently on multicomponent systems.⁸ IUPAC⁹ has reprinted the IUPAC recommendations up to 1990. The nomenclature of polymers was reviewed by Carraher, et al.¹⁰ and more recently by Coleman.¹¹

There are two kinetic schemes for most polymerizations, chain and stepwise polymerization. Table 2¹² provides a brief description of selected chain polymer nomenclature. Table 3¹² provides similar information based on selected stepwise polymer nomenclature. Note the names chain and stepwise, not addition and condensation. The newer terms are broader, and based on kinetics of polymerization.

In general copolymers are defined as polymeric materials containing two or more kinds of mers. However, it is important to distinguish between two kinds of copolymers, those with statistical distributions of mers, or at most short sequences of mers, Table 4,¹³ and those containing long sequences of mers connected together in some way, Table 5.¹³ (The term mer is defined as the individual unit derived from the monomer that makes up the polymer. Thus, when referring to individual units making up a polymer or copolymer, the term monomer should be discouraged to avoid confusion with actual monomers which may be under discussion simultaneously.) Tables 4 and 5 emphasize the connective term joining the mers A, B, C, X, and Y. For example, polyA might represent polyethylene or polyisoprene.

Referring to Table 4, the connective -co- describes an unspecified sequence arrangement of different mers in a polymer. While the older literature used -co- to indicate a statistical copolymer, where the mers appeared in statistical order, the statistical arrangement is now indicated by -stat-. In this latter case, the sequential distribution of mers follows a statistical distribution. A random copolymer is a statistical copolymer in which the probability of finding a given mer at a given site is independent of the nature of the neighboring units at the position. Thus, most mixtures of mers polymerized together to make a polymer should take the term -stat-, and the term -ran- is reserved for those cases where the distribution of mers follow the required mathematical relations.

A very non-random distribution of mers is one where mers A and B alternate. An example of an alternating copolymer is

Poly[styrene-alt-(maleic anhydride)]                     (1)

The term -per- is reserved for three or more mers that form a specific repeating sequence. The newer term net-, a prefix, is included in Table 4 to indicate a polymer crosslinked to form a network.

The various mer sequences delineated in Table 4 can be joined in various ways to form the compositions of Table 5. Figure 1 provides an illustration of the compositions defined in Table 5. An example of a triblock copolymer might be

Polystyrene-block-polybutadiene-block-polystyrene                       (2)

naming a block copolymer widely used for shoe soles and many other applications. In a graft copolymer, the backbone polymer is named first and the side chain is named second. A polymer blend is included here, as a topological case of two polymers in juxtaposition without any bond(y), taking the new connective

-blend-.

A document recommending the terminology of polymeric blends and multi-phase polymeric materials has been submitted by Work to the IUPAC Commission.¹⁴ Recommendations on terms relating to the non-ultimate mechanical properties of polymers were recently published.¹⁵

A polymer blend is defined as a macroscopically homogeneous mixture of two or more different species of macromolecule.¹⁴ The term miscibility is defined as the capability of a mixture to form a homogeneous single phase that is thermodynamically stable with respect to phase separation at least in a certain range of temperature, pressure, molar mass distribution, and compositiona.¹⁴ The term microdomain structure, also called microphase morphology, is defined as microscopic, phase domain-separated morphologies observed in block copolymers that have immiscible blocks.¹⁴ Multiple inclusion morphology, sometimes called salami-type morphology,¹⁴ is defined as a multi-phase morphology in which a single phase domain of one polymer completely encapsulates multiple phase domains of a second polymer. When the material is a rubber-toughened plastic, the terms in use are often rubber cellular domain, within which are occluded cellular domains.¹⁶

Mechanical terms include Young’s modulus, E, defined as the quotient of uniaxial stress (s) and strain (e) in the limit of zero strain,¹⁵

The relaxation time, t, is defined as a time characterizing the response of a viscoelastic liquid or solid to the instantaneous application of a constant strain.¹⁵