Copolymer periodic

Rule 4.1.1 Alternating and periodic copolymers, as far as possible, are treated as regular polymers. 

In periodical copolymers the monomers are arranged in certain ordered sequences ... 

A special case of periodical copolymers are the alternating copolymers. They are composed of two monomers, strictly alternating in the chain, MIM2MIM2M,M2. .. They are designated poly(M,-fl/t-M2) [3],... 

Various blocks may even be statistical or periodical copolymers. Block copolymers are also formed by the combination of suitable end groups of homopolymers of various monomers. This may occur either by direct combination or by means of a bonding group. According to the IUPAC nomenclature [3] these copolymers are designated as polyMl-A/or/ -polyM2-/>/c>cA --polyMj-6/ocfc-polyM... 

Until recently periodic copolymers (consisting of more than two monomers) have been a more or less theoretical domain, treating special kinds of polycondensations rather than polymerizations. Not long ago, donor—acceptor complexes (often zwitterions) composed of two or more compounds (monomers) were discovered, homopolymerizing as a whole to yield periodic polymers. 

Zwitterions formed in this way can mutually combine yielding a ternary, periodic copolymer. An example of this kind of copropagation is the copolymerization of the three units... 

The number of this kind of periodic copolymer is rapidly increasing [238]. The existence of DA complexes naturally offers a much broader choice for the synthesis of alternating copolymers. 

The properties of block copolymers are determined by block composition (a block may be a homopolymer, a statistical or periodic copolymer), block length, and the number and arrangement of the blocks. Block copolymers have the perspective of meeting the demanding requirements of modern plastics applications. 

For source-based representations, lUPAC recommends that alternating and periodic copolymer names contain the connectives -alt- and -per-, respectively. 

Regular (or periodic) copolymer stmctures like (AAAB) (see Figure 4(c)) involve repetition of identical fragments they are similar to homopolymers except that copolymer repeat groups are derived from a number of different monomer units. Random (or statistical) copolymer sequences do not show any periodicity nth unit of a statistical copolymer can be either A or B type with certain probabilities (say, p and 1 - p, respectively). A long statistical copolymer can be charaaerized by the correlation function C(s] =PAA(n,n + s]-p, where PAA(n,n+s) is the probability that the chemical units at positions n and n+s along the chain are both of type A. In the simplest case of a Markovian sequence the correlation function exponentially decays with the distance s ... 

Periodic copolymer A copolymer consisting of macromolecules comprising more than two species of monomeric units in regular sequence. 

The alternating copolymer is the simplest case of a periodic copolymer. For three mers. 

If two or more monomeric units are used to make one polymer, a copolymer is formed. The statistical, random, alternating, and periodic copolymers show the relationship of two mers on an individual basis. The block, graft, AB-cross-linked, and interpenetrating polymer network copolymers comprise large portions of chain or chains containing only one mer. It must be pointed out that each of these may be subject to being composed of the various tac-ticities and so forth that describe the configurational properties. 

Fig ure 3.6 Synthesis of periodic copolymers by step-growth CuAAC of sequence-controlled a-alkyne-, (D-azido-heterotelechelic pre-... 

Fig ure 3.11 Flow iterative growth strategy reported by Johnson, Jamison, and coworkers for the synthesis of monodisperse periodic copolymers. 

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