Polymer compounds classification

Polymers are often divided according to whether they can be melted and reshaped through application of heat and pressure. These materials are called thermoplastics. The second general classification comprises compounds that decompose before they can be melted or reshaped. These polymers are called thermosets. While both thermoset and thermoplastic polymers can be recycled, thermoplastic recycling is easier and more widespread because thermoplastic materials can be reshaped simply by application of heat and pressure. 

Current classification of chemical substances is also limited in reflecting the structural characters of polymer compounds. Chemical substances can be divided into pure substances and their mixtures. The pure substances can be further divided into elements and compounds. Polymer compounds, as a typical soft matter, can change their molecular shapes (conformations) to a large extent, and may contain multiple chemical components in each macromolecule to behave like a mixture. Accordingly, as pure substances, they are more complicated than normal small molecular compounds. In 1990, Wunderlich proposed to divide all chemical compounds into three classes (Wunderlich 1990) ... 

Several kinds of classification methods are used for polymer compounds. 

There is an extremely wide range of potentially useful chemical treatments available, and for any boiler system, proper selection, utilization, and control are vital considerations that may largely determine the ultimate success of the overall program. These chemicals usually are organized by type of compound, function, mode of action, or similar classification, but, because many chemicals are multifunctional in character, may be used in either a primary or supplementary (adjunct or conjunctional treatment) role, and additionally may be branded (especially many modem polymers) or otherwise disguised, such classifications may be quite arbitrary. 

The chemical and physical properties of the polymers obtained by these alternate methods are identical, except insofar as they are affected by differences in molecular weight. In order to avoid the confusion which would result if classification of the products were to be based on the method of synthesis actually employed in each case, it has been proposed that the substance be referred to as a condensation polymer in such instances, irrespective of whether a condensation or an addition polymerization process was used in its preparation. The cyclic compound is after all a condensation product of one or more bifunctional compounds, and in this sense the linear polymer obtained from the cyclic intermediate can be regarded as the polymeric derivative of the bifunctional monomer(s). Furthermore, each of the polymers listed in Table III may be degraded to bifunctional monomers differing in composition from the structural unit, although such degradation of polyethylene oxide and the polythioether may be difficult. Apart from the demands of any particular definition, it is clearly desirable to include all of these substances among the condensation... 

In this classification of the compounds into mucopolysaccharides, mucoproteins, and mucolipids, it must be emphasized most strongly that since the mode of isolation of any naturally occurring high polymer influences profoundly its composition and biological properties, the difference between divisions is not always sharp and there may be some degree of overlapping. 

In many cases, these polymer chains take on a rod-like (calamitic LCPs) or even disc-like (discotic LCPs) conformation, but this does not affect the overall structural classification scheme. There are many organic compounds, though not polymeric in nature, that exhibit liquid crystallinity and play important roles in biological processes. For example, arteriosclerosis is possibly caused by the formation of a cholesterol containing liquid crystal in the arteries of the heart. Similarly, cell wall membranes are generally considered to have liquid crystalline properties. As interesting as these examples of liquid crystallinity in small, organic compounds are, we must limit the current discussion to polymers only. 

Polymer identification starts with a series of preliminary tests. In contrast to low molecular weight organic compounds, which are frequently satisfactorily identified simply by their melting or boiling point, molecular weight and elementary composition, precise identification of polymers is difficult by the presence of copolymers, the statistical character of the composition, macromolecular properties and, by potential polymeric-analogous reactions. Exact classification of polymers is not usually possible from a few preliminary tests. Further physical data must be measured and specific reactions must be carried out in order to make a reliable classification. The efficiency of physical methods such as IR spectroscopy and NMR spectroscopy as well as pyrolysis gas chromatography makes them particularly important. 

Major advances and problems in the field of synthesis, properties, structure and applications of polymers containing metallochelate units are discussed. Included are terminology, classification and nomenclature of these compounds as well as major approaches to calculating the equilibrium constants of chelation with polymeric ligands and chelate effect in metallopolymeric systems. Special attention is paid to the production and structural features of polymers containing metallochelate units. The most important applications of such polymers are classified... 

In the following the polymer-bound active compound shall be decisive for the classification and discussion of these types of polymeric drugs. 

Hybrid framework compounds, including both metal-organic coordination polymers and systems that contain extended inorganic connectivity (extended inorganic hybrids), have recently developed into an important new class of solid-state materials. We examine the diversity of this complex class of materials, propose a simple but systematic classification, and explore the chemical and geometrical factors that influence their formation. We also discuss the growing evidence that many hybrid frameworks tend to form under thermodynamic rather than kinetic control when the synthesis is carried out under hydrothermal conditions. Finally, we explore the potential applications of hybrid frameworks in areas such as gas separations and storage,... 

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