Polymer nomenclature molecular weight

This nomenclature primarily answers three questions about the chemical entity (1) which polymers are combined, (2) principal modes of combination, and (3) the time sequence of reaction. Other items of information, such as weight proportions, molecular weights, morphology, tacticity, etc. can be included as ancillary items but will not be discussed in detail below. 

The molecular weight dependence of the critical concentration for the establishment of uniformly anisotropic solutions of PBG is shown in Table I for various solvents that we have examined. Volume fractions ij>) of polymer quoted in this compilation correspond to the B-point in the nomenclature of Robinson (28-29). The B-point differs from the A-point, a lower concentration where the anisotropic phase just begins to form and is in equilibrium with isotropic polymer solution. 

Physically persistent stabilizers classified as functionalized oligomers or polymers can be synthesized by polyreactions of functionalized monomers and/or by polymer analogous reactions exploiting the reactivity of functionalized reactive low molecular weight compounds with polymeric substrates. For a detailed classification of synthetical approaches, the classification principle used in Houben-Weyl [42] was adopted. The nomenclature of functionalized polymers is based on the monomer s unit principle. Abbreviations of conventional polymers are used as recommended by [1, 2]. 

The usual names such as INN (International Non proprietary Names), INNv (proposed International Nonproprietary Names) and other customary names are given in the indexes. In addition, with the spectra of all pharmaceutical substances (with the exception of complex molecules and polymers) the chemical structural formulas and the relative molecular weights are indicated. Therefore the designation by scientific nomenclature has been dispensed with. 

The nomenclature poly (M1-6-M2) is used where Mj and M2 are the monomer names for example poly (styrene-b-butadiene). To make block copolymers, the polymer chains must have the ability to propagate [living polymers) when the first monomer is replaced by the second. In conventional addition polymerisation the chain termination and transfer processes make the lifetime of a growing polymer chain too short. Consequently, special ionic polymerisation catalysts were developed. A fixed number of di-anions such as [C6H5CHCH2CH2CHC6H5] are introduced into an inert solvent. These propagate from both ends if a suitable monomer is introduced. As there are no termination or transfer reactions, once the first monomer has been consumed, a second monomer can be introduced to produce a triblock copolymer such as styrene-butadiene-styrene. Each block has a precisely defined molecular weight. These materials undergo phase separation (Chapter 4) and act as thermoplastic rubbers. 

On the other hand, modern nomenclature is based on the chemical structure of the macromolecules. The name of a polymer of unspecified degree of polymerization consists of the prefix poly and the name of the smallest repeating unit. With unbranched polymers, the smallest repeating unit is a diradical. The name of this diradical is the same as that met with in the nomenclature for low-molecular-weight organic diradicals. Thus, the group —CH2— is called methylene and the corresponding polymer is called poly(methylene) (example 1 in Table 1-4). The diradicals —CH2—CH2— and —CH2—CH(CH3)— do not have simple definitive names the trivial names ethylene and propylene are retained. Examples of names for other diradicals are as follows ... 

Electrically neutral substituents in macromolecular chains exhibit no peculiarities with respect to low-molecular-weight compounds in terms of constitution, nomenclature, or, in general, modes of reaction. Polymers with substituents having ionizable bonds are called polyelectrolytes. Polyelectrolytes can dissociate to form a polyion and an oppositely charged gegenion. They can be polyacids, such as poly(acrylic acid)... 

Fractionation by crystallizability takes place by either decreasing or increasing the temperature, similarly to what is done in the methods of fractional precipitation or coacervate extraction for molecular weight fractionation. However, differently from those, solid-liquid phase separation occurs during fractionation by crystallizability. We will call Crystaf-mode the fractionation that takes place upon cooling the polymer solution, and TREF-mode the fractionation that takes place by dissolving previously precipitated polymer crystallites. This nomenclature is consistent with the continuous analysis techniques of Ciystaf and TREF, which will be described later in this article, and is more adequate for fractionation by crystallizability. 

A polymer may be assigned a unique name, eg, poly(oxy-l,2-ethanediyl) (structure-based) or poly(oxirane) (source-based), but since such nomenclatin-e (see Nomenclature) incorporates no properties such as molecular weight, these names per se are insufficient to distinguish one sample from another. Likewise, any single complete molecular formula that represents a discrete molecule within the polymer is inadequate to describe the whole polymeric mixtin-e, and to write a molecular formula for every distinct molecule present in a polymer would be hopeless. Therefore, compromises must be made. This article describes the current situation with regard to structural representation of polymers. 

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