Polymers hetero-chain

Oxo-Biodegradable Polyolefins Carbon-chain polymers Hetero-chain polymers... 

The hetero-chain polymers are mainly made by elimination of water between a carboxylic acid and an alcohol or an amine to give a polyester or a polyamide respectively. These are the condensation polymers ... 

The hetero-chain polymers, notably the polyesters, polyamides and polyurethanes, can also act as a source of new monomers or oligomers by hydrolysis and alcoholysis. This recycling process (sometimes called... 

Among the large variety of hetero-chain polymers we are also interested in polycarbonates, one of which, the polycarbonate of bisphenol-A (PC), is also depicted in Fig. 2.3, even though it is not exactly a condensation polymer. 

Hetero-chain polymers involving the amino group might be expected to be unstable in aqueous environments and especially biological environments. Polymers of the nylon variety and poly(amino acid)s are briefly mentioned here. 

Stmctures with the widest temperature range of demonstrated stabiUty have fluorine in the gamma position relative to siUcon (or further removed), as in CF2CH2CH2SiIlR R. Longer hydrocarbon chains, with or without hetero atoms, are feasible, but oxidative stabiUty is compromised and such materials are generally disfavored. Poly(3,3,3-trifluoropropyl)methylsiloxane [26702-40-9] demonstrates this stmctural principle. This polymer is one key member of the industrially important family of fluorosiUcone materials. 

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. 

Polymers with hetero-atoms in the chain are suitable for chemical recycling of waste materials. In addition to depolymerisation (nylon 6) and solvolysis (nylon 6,6, PETP, PU) the degradation of aliphatic polyamides with dicarboxylic acids, diamines and cyclic anhydrides, especially trimellitic anhydride, becomes more and more important. The utilisation of the obtained fragments is described. 

Neat DNA, because of its hybridization and complementarity behavior, is an obvious candidate as a synthon for nanostructures. Because naturally occurring DNA is a hetero-polymer, and because of all the structural disorder inherent in any DNA chain, such properties as coherence, transport, persistence length, and structure are expected to differ substantially among samples of DNA that have the same chemical composition. On the basis of this propensity for disorder, the statement that this ignorance (of DNA transport) is justified by the complexity of the problem is understandable [52]. 

Polynuclear inorganic compounds exist in a bewildering array of structural types, such as ionic solids, molecular polymers, extended assemblies of oxounions both of metals and nonmeinis, nonmetal chains and rings, bridged melui complexes, and homo- and hetero-nuclcar clusters. This section treats primarily the nomenclature of bridged metal complexes and homo- and hetero-nuclear dusters. 

Self-Organization of Supramolecular Liquid Crystalline Polymers from Complementary Components. If two (or more) complementary units e or 3 are grafted on a template T, mixing Te m with the complementary T3m may lead to the hetero-self-assembly of a linear or cross-linked, main-chain supramolecular copolymer species (Te m, Tsw), whose existence is conditioned by the molecular recognition-directed association between the e and a groups. 

---