Heterochain polymer

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. 

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. 

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. 

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 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. 

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. 

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... 

B. M. Povarskaya, A.B. Blumenfel d, 1.1. LEvantovskaya, Thennal stability of heterochain polymers. Moscow, Chemistry (1977) (in Russian). 

F.F. Niyazi, Stabilization of heterochain polymers at photo- and thermodestruction and their modification by the additives of multifunctional action. Author s abstract of doctor dissertation, Dushanbe (1993) (in Russian). 

Photochemical reactions in heterochain polymers / Farukh fatekhovich Niyazi... [Et al.], editors. 

Heterochain polymers. 2. Photodegradation. 3. Polymers—Deterioration. 4. Polymers—... 

The polyurethanes are a special group of heterochain polymers, characterised by the following structural unit [1-33] ... 

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. 

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