Other Heterochains

Obtained polyetherimides are of interest as easily processed polymers on the standard equipment. Synthesized polyetherimides can be used as thermoreactive polymers, their mixes with other heterochained and heterocyclic polymers also are of interest with the purpose of obtaining the composite materials with high chemical and fire resistance. 

Among the abundance of tested classes of substances, PCA is the only additive reliably protecting PSF from oxidation in concentrations below 0.3 wt.%. As expected, by analogy with polycarbonate and other heterochain polymers processed at temperatures about 300°C, classical primary antioxidants (hindered phenols and aromatic amines) are at most neutral (amines catastrophically color PSF), which proved existence of the effective inhibition temperature limit (120 - 125°C) [11, p. 218]. It is stipulated by activity of phenoxyl radicals in reactions with hydroperoxides. Commonly, all so-called non-chain inhibitors intensify... 

Andrianov and Zhdanov have developed a method for the synthesis of polymers containing heterochain and carbon-chain units by free-radical copolymerization of metal-containing polyorganosiloxanes bearing a pendant vinyl group with vinyl monomers. The copolymers thus obtained display increased thermal stability and can be used for the production of laminated plastics, adhesives and other valuable materials 53),... 

This article surveys the research work on the synthesis and modification reactions of poly(ethyleneimine) as well as its applications to metal complexation processes. Poly-(ethyleneimine), one of the most simple heterochain polymers exists in the form of two different chemical structures one of them is branched, which is a commercially available and the other one linear which is synthesized by cationic polymerization of oxazoline monomers and subsequent hydrolysis of polyf(/V acylimino)cthylcne]. The most salient feature of poly(ethyleneimine) is the simultaneous presence of primary, secondary, and tertiary amino groups in the polymer chain which explains its basic properties and gives access to various modification reactions. A great number of synthetic routes to branched and linear poly(ethyleneimine)s and polymer-analogous reactions are described. In addition, the complexation of polyfethyleneimine) and its derivatives with metal ions is investigated. Homogeneous and heterogeneous metal separation and enrichment processes are reviewed. 

Heterochain polymers, which may have other atoms (originating in the monomer functional groups) as part of the chain. These polymers are usually prepared by polycondensation or step-reaction polymerisation. 

Otherwise, the heterochain polymers that contain heteroatom as part of the chemical constitution of the polymer along the main chain, besides degradation described for homopolymers, and also other mechanisms may be considered in their degradation mode, that is, depolymerization or elimination reactions. 

On the other hand, controlled branching in crystalline, homochain polymers, such as polyethylene, has been used as a strategy to broaden the distribution in crystallite size, lower the overall degree in crystallinity, and increase compliance. A similar but more difficult to implement approach to achieving such an effect on crystallinity, as alluded to above, has been used specifically in the production of linear segmented and block heterochain copolymers such as ... 

Isochains consist of identical main chain atoms. Heterochains have two or more different kinds of atoms in the main chain. Isochains are very readily formed by carbon atoms, but less readily, however, by other elements. Chains containing no carbon atoms in the main chain are also known as inorganic chains. 

Isochains and heterochains may be substituted or unsubstituted. Here, the different significances of the word substitution in inorganic and organic chemistry must be noted. In the strictest sense, unsubstituted isochains occur in cflr/ na-poly(sulfur). On the other hand, silanes, H(SiH2)nH, should be considered as substituted in the sense of inorganic nomenclature. By contrast, the poly(alkanes), H(CH2)nH, are considered to be unsubstituted chains in organic chemistry, since the basic structure is here considered to be the alkanes, and not diamond. 

The reactions of polycondensation are the bases of producing the most important classes of heterochain polymers polyarylates, polysulfones, polyarylenesterketones, polycarbonates, polyamides and others [7-12],... 

In addition to carbon, many other elements can form chain structures with themselves or with other elements. Polymers that do not contain carbon atoms in the main chain are called inorganic polymers. According to the kinds of elements in the main chain, they are classed as isochains or heterochains, and, depending on the kind of linkage in the chains, they are called linear chains, ladder polymers, parquet polymers, or lattice polymers (see also Chapter 2). 

All elements that form isochains can also form heterochains with other elements. In addition, simple heterochains can sometimes be formed by the next higher row of the periods III, IVB, and VB, namely aluminum, iron, and bismuth. Compounds with multicenter bonds are also formed by beryllium and a few elements from higher rows, e.g., niobium and vanadium. In these compounds, as well as the OH and H groups, the elements of period VIIB can also occur as the central atoms in multicenter bridge bonding, that is, in borohydrides, niobium iodide, etc. These elements, however, do not represent true chain atoms. 

The utility of silicones has lead to the synthesis of many other inorganic heterochains containing main-chain oxygen. Aluminoxanes, with... 

Cazacu, M., Polymers Containing Si, O, and Other Elements Within Backbone. In Advances in Functional Heterochain Polymers, Cazacu, M., Ed. Nova Science New York, 2008 pp 1-32. 

Each class of polymer can be divided into various subclasses. The subclasses are determined by the elements of the main chain. The most important subclasses of homochain pmlymers are carbon-chain polymers. Nevertheless, other subclasses exist [89IUP2]. Subclasses of homochain and heterochain polymers are listed in Table 2.1.3. 

This work is devoted to systematic study of gas transport parameters of polycarbosilanes obtained from silicon-containing cyclic monomers. This approach allowed us to synthesize carbochain and heterochain polymer femilies with regularly varied substituents at Si atom. On the other hand, such research on polymer series of different classes leads to basic correlations and helps one to understand relationships between features of polymer chemical structure and its gas separation characteristics. 

Heterochain (co)polymers with Choi pendant groups have been prepared by ROP. A cyclic phosphate monomer with Choi moiety (Fig. 8f) has been prepared and copolymerized with two other cyclic phosphate monomers followed by ATRP graft polymerization to introduce hydrophilic side chains [207]. The Choi moieties help this amphiphilic polyphosphate-based graft copolymer to form stable associations in water and to improve the encapsulation of anticancer drugs. 

Table 1 shows some problems in heterochain copolymer composition and structure which have been studied by NMR. Other methods which have given useful information include the use of an isotopically labelled monomer to investigate preferential incorporation during copolymerization the application of isotopic dilution analysis to polymer degradation products to determine the proportion of isolated units of a particular component and the use of mass spectrometry to determine blockiness. ... 

Although the plastics industry uses both classes of polymers, most thermoset plastics are based on heterochain polymers such as the urethane, epoxy, and aldehyde condensation resins. Thermoplastics, however, are mainly based on carbon chain polymers (with the notable exceptions of polyesters, nylons, and a few others). 

Two other polymer-based industries are found to depend more on one class than the other. The rubber industry uses both carbon chain and heterochain polymers. A generic classification of elastomers suggested by the American Society for Testing and Materials (ASTM) indicates no bias toward carbon chain polymers [1]. However, the seven heterochain rubbers listed in Appendix 16.A probably constituted less than 5% of the total rubber produced in 2000. The reasons for this situation appear to be economic and historical rather than fundamentally physical or chemical. Heterochain polymers of excellent strength, resilience, and durability have been designed, but never at a price that attracted widespread use. 

---