Heterochain

Sukhorukov, B. J., Kuz menko, V. A., Blumenfeld, L. A. in collected articles Geterotsepnyl vysokomolekularniye soedineniya (heterochain high-molecular compounds), 1964... 

Heterochain polymers produced by ring-opening polymerization contain the hetero-atoms in the main chain as well as in the monomer and the polymer chain competes with the monomer for the reaction with the propagating species. This competition leads to polymer transfer and back-biting reactions during the polymerization. Heterochain polymers are also susceptible to depolymerization by the ionic active species which are easily formed during processing. 

Several important assumptions are involved in the derivation of the Mayo-Lewis equation and care must be taken when it is applied to ionic copolymerization systems. In ring-opening polymerizations, depolymerization and equilibration of the heterochain copolymers may become important in some cases. In such cases, the copolymer composition is no longer determined by die four propagation reactions. 

Because of the great differences in the properties between vinyl polymers and heterochain polymers, copolymerization of a vinyl monomer and a cyclic monomer seems very intersting. Yet, little success has been achieved in the formation of random copolymers because the reactivities are very different between vinyl monomers and cyclic monomers. However, recent progress in the field of organic chemistry has suggested many possibilities especially for the activation of monomers and for the modification of the reactivity of the propagating species. The probability of successful synthesis of random copolymers has thus greatly increased. 

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),... 

Slonim IYa, Urman YaG (1982) NMR Spectroscopy of Heterochain Polymers. Khimiya, Moscow, p 87 (in Russian)... 

Some of the heterochain polymers are given below. The polymeric structure of hydrogen boride can be represented as under ... 

Of various heterochain polymers polyaminotriazoles are found to be the most stable to hydrolysis they are soluble in cyanohydrins and polyhydric alcohols. 

Heterochain polymers Heterochain polymers Aliphatic polymers with quaternary carbons Unsaturated polymers Amorphous polymers Heterochain polymers Vinyl polymers Polymers below... 

Most heterochained polymers, including condensation polymers, are susceptible to aqueous-associated acid or base degradation. This susceptibility is due to a combination of the chemical reactivity of heteroatom sites and the materials being at least wetted by the aqueous solution allowing contact between the proton and hydroxide ion. Both these factors are related to the difference in the electronegatives of the two different atoms resulting in the formation of a dipole that acts as a site for nucleophilic or electrophilic chemical attack and that allows polar materials to come in contact with it. Such polymers can be partially protected by application of a thin film of hydrocarbon polymer that acts to repel the aqueous solutions. 

At the same time, the macromolecules might be classified according to whether their chains have only one kind of atoms - like carbon - in the backbone (isochains) or different elements (heterochains). Concerning their chain architecture, polymers are subdivided into linear, branched, comb-like, crosslinked, dendritic, or star-like systems. 

The mechanical synthesis of block and graft copolymers by vibromilling a polymer-monomer blend has been performed by many researchers. Natural polymers (14,17) vinyl polymers (18—27), and heterochain polymers (18, 28-34) have been formed during polymer mechanochemical degradation. Importantly, Simionescu, Vasiliu-Oprea and Neguleanu studied the possibility of carrying out mechanically-induced polycondensations starting from polyesters and diamines (33,35-37). 

Polyesters. Simionescu and coworkers continued their syntheses of heterochain polymers by investigation extensively the hehavior of polyethylene tere-phthalate by the vibromilling in the presence of different monomers. They achieved... 

The presence of a comonomer has, in certain cases, 9 marked influence on polymerization rate. For example, the mastication of natural rubber in the presence of maleic anhydride, even with small concentrations of the latter, about 5%, leads to accelerated polymerization of styrene monomer (11) either because of its high reactivity in the propagation step of heterochain copolymerization and/or because of a hardening effect. This reaction is discussed later. 

The mechanochemical polycondensation reaction has been studied using heterochain polymer systems—polyethylene terephthalate poly-(e-caprolactam), cellulose, etc.—characterized by end groups that can be activated to increase their own number by mechanochemical destruction of corresponding polymers. The mechanochemical destruction was done in the presence of some suitable condensing agents, such as aliphatic and aromatic diamines and fatty acid dichlorides. 

Thermal Stability of Engineering Heterochain Thermoresistant Polymers E. VKalugina, K.Z. Gumargalieva and G.E. Zaikov... 

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. 

V. C. Pshezhetskii and V. I. Tupikov, Heterochain High-Molecular- Weight Compounds, 1964, pp. 220-226 (in Russian). 

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. 

Heterochains are usually built up according to the following scheme (per structural unit) ... 

Fig. 9.2. Main types of (a) homopolymers and (b) heterochain synthetic polymers found in plastics (adapted from McNeill, 1991).

The presence of macrocycles of various size in heterochain polymers prepared by polycondensation or polymerization is a well known phenomenon This is due to reactions discussed in the preceding sections of this review and can be simply presented as a result of back-biting (including end-biting) reactions (the influence of end-biting will be discussed separately) ... 

Photosensitive polymers Heterochain polymers, nitrogen-containing polymers, polyesters Vinyl polymers Aliphatic polymers with quaternary carbon atoms... 

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