Synthetic polymers classification

Biodegradable polymers and plastics are readily divided into three broad classifications (/) natural, (2) synthetic, and (J) modified natural. These classes may be further subdivided for ease of discussion, as follows (/) natural polymers (2) synthetic polymers may have carbon chain backbones or heteroatom chain backbones and (J) modified natural may be blends and grafts or involve chemical modifications, oxidation, esterification, etc. 

Different classifications for the chiral CSPs have been described. They are based on the chemical structure of the chiral selectors and on the chiral recognition mechanism involved. In this chapter we will use a classification based mainly on the chemical structure of the selectors. The selectors are classified in three groups (i) CSPs with low-molecular-weight selectors, such as Pirkle type CSPs, ionic and ligand exchange CSPs, (ii) CSPs with macrocyclic selectors, such as CDs, crown-ethers and macrocyclic antibiotics, and (iii) CSPs with macromolecular selectors, such as polysaccharides, synthetic polymers, molecular imprinted polymers and proteins. These different types of CSPs, frequently used for the analysis of chiral pharmaceuticals, are discussed in more detail later. 

The use of PCA for the classification of both natural and synthetic polymers was demonstrated by Vazquez et al. [119]. In their work, the researchers recorded Totai X-Ray Fluorescence (TXRF) spectra of scleroglucan, xanthan, glucomannan, poly(ethylene oxide), and polyacrylamide and subjected the resulting spectral data to PCA. To the naked eye, the X-ray fluorescence spectra of the polymers look virtually identical. However, when subjected to PCA it could be shown that the first two principal components contain approximately 96% of the variance in the dataset. When plotting the scores of the two components against each other, six distinct clusters are observed, which clearly differentiate the individual polymers. 

Various criteria can be considered in the classification of the SEC applications. The most important are the analytical SEC procednres. The preparative applications, which encompass the purification of complex samples before their further treatment, draw rather wide attention. In this latter case, analytes are preseparated by SEC according to the size of their components and either macromolecular or low molecular fractions are subject to further analyses by other methods. The production oriented SEC did not find wide application in the area of synthetic polymers due to both the high price of organic solvents and the ecological considerations. 

In addition to the classification of liquid chromatographic enantioseparation methods by technical description, these methods could further be classified according to the chemical structure of the diverse CSPs. The chiral selector moiety varies from large molecules, based on natural or synthetic polymers in which the chirality may be based on chiral subunits (monomers) or intrinsically on the total structure (e.g., helicity or chiral cavity), to low molecular weight molecules which are irreversibly and/or covalently bound to a rigid hard matrix, most often silica gel. 

POLYAMIDE RESINS. These are synthetic polymers that contain an amide group, —CONH-. as a recurring part of the chain. Poly-alpha-aminoacids, i.e., proteins, whether natural or synthetic, are not normally included in this classification. 

According to our earlier classification, the stationary phase can be a solid, a liquid, or a bonded phase. In the latter two cases, the phase must be coated on, or bonded to, particles of a porous solid support. Only a few materials have found widespread use as stationary solid supports they are silica, synthetic polymers such as the styrene-divinylbenzene copolymer, diatomaceous earths, and some polysaccharides. The most common types and uses are given in Table 2. 

TABLE 1 Classification of Natural and Synthetic Polymers and Their Methods of Purification or Synthesis... 

Monomers can be joined by means of two principal methods to form polymers, and these methods are used as the broad basis for classification of synthetic polymers. The first of these, condensation, or step-growth polymerization, involves the use of functional group reactions such as esterification or amide formation to form polymers. When each of the molecules involved has only one functional group then the reaction between a carboxylic acid and an alcohol gives an ester (Eq. 20.3). In this equilibrium reaction water removal will help drive the reaction to the right. 

In contrast with the usually slow progress of condensation polymerization the second major classification, addition, or vinyl-type polymerizations, usually proceed very rapidly, so rapidly that they are referred to as chain reaction polymerizations. This method of producing synthetic polymers uses the potential dual functionality present in a carbon-carbon double bond. The process is initiated by the use of radical or charged initiator species to form new sigma bonds from the carbon-carbon double bonds of the monomer, to link the monomer units (Eq. 20.6). 

Origin Another possible classification of polymeric substances can be based on the origin of the material or the repeating units. In this sense, one can have natural and synthetic polymers, if they occur in nature or if they are synthesized in a chemical laboratory, respectively. Of course, natural polymers are of great importance, but they fall out of the scope of this handbook, which is mainly concerned with synthetic polymers. 

Polymers can be classified in many different ways. The most obvious classification is based on the origin of the polymer, i.e., natural vs. synthetic. Other classifications are based on the polymer structure, polymerization mechanism, preparative techniques, or thermal behavior. 

Synonyms Polysulfide elastomer Classification Synthetic polymer... 

Classification Synthetic polymer Properties Solid or liq. exc. low-temp, flexibility exc. resist, to oils and soivs. exc. impermeability to gases poor tensile strength and abrasion resistance... 

Membrane classification can be done according to several viewpoints. A major division can be made between biological and synthetic membranes. Biological membranes are semi-permeable barriers that separate either the inside from the outside of the cell, or enclose internal cell structures, but these will not be addressed in this work. Commonly used membranes in separation or bioconversion processes are made of synthetic polymers or ceramics (Table 4). 

It is difficult to make a distinct classification of biodegradable polymers. Many authors have classified them according to their origin as natural or synthetic polymers. Both of these are subdivided into different classes based on the main linkages present in their structure. Thus completely biodegradable natural polymer subclasses include polysaccharides, polypeptides, polyesters, lipids, natural rubber and natural composites (wood). Partially biodegradable synthetic polymer subclasses include polyesters, polyur eas, polyurethanes, polyamides, poly( vinyl alcohol) and poly (ethylene glycol). 

Chiral stationary phases that are currently available can be classified into those containing cavities (cellulose derivatives, cyclodextrins, synthetic polymers, crown ethers, and chiral imprinted gels), affinity phases (bovine serum albumin, human serum albumin, a-glycoprotein, enzymes), multiple hydrogen-bond phases, Ti-donor and Ti-acceptor phases, and chiral ligand exchange phases. This classification scheme was used in a review that gave numerous pharmaceutical examples of separation by... 

Polymers can be classified in various ways. The most obvious is to think of them as either being natural or synthetic. This is the classification used in this book. Alternative ways of classification are based on their use (structural and non-stmctural polymers) and their characteristics (degradable and non-degradable polymers). These aspects are discussed in the first chapter. This chapter will give an overview of the synthetic and natural degradable polymers. However, overall, the book focuses on the synthetic polymers used for biomedical appfications. Amongst the class of synthetic polymers, this chapter will discuss polyesters, polycarbonates, and polyurethanes, the most commonly used synthetics polymers for biomedical appfications. 

We will conform to Carothers classification in the sections devoted to the preparation of synthetic polymers. However, when considering the application of polymers it is more useful to consider the following three categories (1) plastics, which include thermosetting resins, such as urea resins, polyesters, or epoxies, and thermoplastic resins, such as poly-... 

Polymers can be categorized by a number of methods. One technique is to separate them broadly into classifications of natural, or biological, polymers and nonbiological, or synthetic, materials. Whereas synthetic polymers are of fairly recent vintage, natural polymers go back into prehistory. Cellulose, the chief component of plant cell walls, and protein, an essential component of all living cells, are both polymers. Hence, plants and animals are in large measure polymeric in nature. 

A synthetic polymer is manufactured in industry from chemical substances through polymer building processes. Even synthetic polymers can be classified in different ways. Considering typical applications, the following classification makes sense (the used abbreviations are explained in Table 5.4.1 and Table 5.4.2.) ... 

Table 4.1 Classification of fiber-forming hydrolytically sensitive bioresorbable synthetic polymers...

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