On macromolecular chains

Table 1 - Overview of cooperative effects on macromolecular chain...

Neutral substituents on macromolecular chains require no special treatment in terms of constitution or nomenclature to differentiate them from low-molar-mass substances. Practically all the groupings and classifications of low-molar-mass organic, organometallic, and inorganic chemistry can be used with substituents on macromolecular chains. 

Wang, K., Liang, S., Deng, J., Yang, H., Zhang, Q., Fu, Q. et al. 2006. The role of clay network on macromolecular chain mobility and relaxation in isotactic pol5 ropylene/organoclay nanocomposites. Polymer 47 7131-7144. 

In order to "cure" or "vulcanize" an elastomer, ie, cross-link the macromolecular chains (Fig. 2), certain chemical ingredients are mixed or compounded with the mbber, depending on its nature (4,5). The mixing process depends on the type of elastomer a high viscosity type, eg, natural mbber, requires powerhil mixers (such as the Banbury type or mbber mills), while the more Hquid polymers can be handled by ordinary rotary mixers, etc (see Rubber... 

Chemical modification of polymers (J.) still remains a field of continuously increasing importance in macromolecular chemistry. In spite of its high diversification, it may be divided into 2 distinct but complementary main research lines a) the fundamental study of the chemical reactivity of macromolecular chains b) the synthesis of new homopolymers and copolymers, and the functionalization of linear or crosslinked polymers. Some of these facets have been reviewed in the last years (2-6), and the purpose of this presentation is to illustrate a number of characteristic topics both from fundamental and applied points of view, through some literature data and through our own studies on nucleophilic substitution of polymethylmethacrylate (PMMA). 

Quite recently, Plate and Noah — have critically discussed all the theoretical aspects of macromolecular chain reactivity, and we summarize below the main conclusions related to the processes of interest in our studies kinetically controlled irreversible reaction of a low molecular weight compound R on an homopolymer An, involving a single monomeric unit A. 

Copolymers bearing keto-fj-heterocyclic units COCH Het are good systems for the comparative study of the specific tautomeric equilibrium of the B units (42) on model compounds (CH ) CCOCH Het. and on well defined macromolecular chains ... 

On the other hand, two important factors of macromolecular chain reactivity in solution deserve more attention,namely the nature of the reaction medium and the polymer concentration. 

From a theoretical and mechanistic point of view, small molecule rings are much easier to study than long macromolecular chains. Substitution reactions carried out on macromolecular... 

The theoretical and methodological aspects of conformational analysis of macromolecular chains in the disordered state were discussed by Flory in his classic book (155, 187). The literature on the subject includes a large number of books and reviews (37, 39, 188-190) extensive discussions may also be found in general textbooks of macromolecular science (9, 12, 13, 191). 

The formation of synthetic polymers is a process which occurs via chemical connection of many hundreds up to many thousands of monomer molecules. As a result, macromolecular chains are formed. They are, in general, linear, but can be branched, hyperbranched, or crosslinked as well. However, depending on the number of different monomers and how they are connected, homo- or one of the various kinds of copolymers can result. The chemical process of chain formation may be subdivided roughly into two classes, depending on whether it proceeds as a chain-growth or as a step-growth reaction. 

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