Branched copolymers, definition

So far in our discussion of micros tincture, we have considered homopolymers. To some degree, however, there is an element of semantics involved in our definition. Is a branched polyethylene a true homopolymer or should it be considered a copolymer of ethylene and whatever units comprise the branches Here our concern is real copolymers, those synthesized from two (or more) distinct monomers. The simplest possible arrangements are shown in Figure 2-22 and are self-explanatory. But, as we will see, real life is more complex. True random copolymers are rare and in most cases there are tendencies to blockiness or alternating arrangements. There are also graft copolymers, but we will discuss all this in more detail when we consider copolymerization. 

In graft copolymerization, there are also sequences of Mj and sequences of M2, but they are formed at branch points, so all graft copolymers are, by definition, branched. These are also formed in sequential reactions, and graft copolymerization is frequently employed in reactive processing. 

Summarizing the above description, the surface of polyamine graft copolymers with a definite amount of polyamine branches showed an extremely small quantity of non-specifically adsorbed lymphocytes. This advantageous characteristic of polyamine graft copolymers led us to utilize them as solid-phase matrices for cell affinity chromatography. 

As a more general structural definition, a polymer synthesized from only one type of monomer is referred to as a homopolymer. In contrast, a polymer that is formed from more than one type of monomer is known as a copolymer. The terms terpoly-mer, tetrapolymer, pentapolymer, etc. are used to designate a polymer derived from three, four, five, etc. co-monomers. Although homopolymers contain only one repeating chemical unit in their structure, this distinction is not always clear. For instance, polyethylene polymers often contain short-chain branched impurities as a consequence of the polymerization process. However, since this unintentional structural deviation results from a polymerization process involving only one type of monomer, the term homopolymer is still most appropriate. 

A polymer, by conventional definition, is a macromolecule made up of multiple equivalents of one or more monomers linked together by covalent bonds (e.g., carbon-carbon, amide, ester, or ether bonds) [1]. These conventional polymers come in many configurations for example, linear homopolymers, linear copolymers, block copolymers, crosslinked polymers, dendritic polymers, and others. The most common architecture for polymers is based on linear chains that may have other attached chains (branched, grafted, or crosslinked) that is, they are one-dimensional molecules. A few examples have been claimed as two-dimensional sheet polymers. ... 

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