Macromolecules polyfunctional

The steady structure determined by the value of Kw (Fig. 1) for the entire class of carboxylic CP obtained by precipitation copolymerization is one of the most important factors determining the possibility of reversible bonding of proteins absorbed by carboxylic CP with a high sorption capacity [16,19]. Thus, for the MA-HHTT system (Fig. 2), a complete desorption of enzyme is carried out on crosslinked copolymers characterized by low Kw values. In crosslinked structures exhibiting looser structure (Kw P 1), owing to the mobility of chain fragments of CP especially in the process of desorption, the macromolecules of sorbed protein are irreversibly captured as a result of a marked polyfunctional interaction. 

In 1941, Flory80 introduced the concept of hyperbranched macromolecules by polymerization of a trifunctional AB2 monomer (Fig. 5.16). From a chemical point of view, perfectly defined structures were obtained when the monomer reactions were performed step by step At each step, a polyfunctional molecule... 

This group covers polymeric peroxides of indeterminate stmcture rather than polyfunctional macromolecules of known stmcture. These usually arise from autoxidation of susceptible monomers and are of very limited stability or... 

Polyurethanes are macromolecules in which the constitutional repeating units (CRUs) are coupled with one another through urethane (oxycarbonylamino) groups. They are prepared almost exclusively by stepwise addition polymerization reactions of di- or polyfunctional hydroxy compounds with di- or polyfunctional isocyanates ... 

Functionally terminal polymers are valuable material intermediates. The di- and polyfunctional varieties (telechelic polymers) have found theoretical (e.g., model network) and commercial (e.g., liquid rubber) applications (1, ). On the other hand, macromolecules with a functional group at one chain end (semitelechelic polymers) have been used to prepare novel macromolecular monomers (Macromers ), as well as block and graft copolymers ( -8). 

Branched polyfunctional molecules of star-like and comb-like types are often encountered and, therefore, it is necessary to examine the effect of branching on the chromatographic behaviour of a macromolecule near the critical point. 

This group covers polymeric peroxides of indeterminate structure rather than polyfunctional macromolecules of known structure. These usually arise from autoxidation of susceptible monomers and are of very limited stability or explosive. Polymeric peroxide species described as hazardous include those derived from butadiene (highly explosive) isoprene, dimethylbutadiene (both strongly explosive) 1,5-p-menthadiene, 1,3-cyclohexadiene (both explode at 110°C) methyl methacrylate, vinyl acetate, styrene (all explode above 40°C) diethyl ether (extremely explosive even below 100°C ) and 1,1-diphenylethylene, cyclo-pentadiene (both explode on heating). 

J. Wyman, A group of thermodynamic potentials applicable to ligand binding by a polyfunctional macromolecule. Proc. Nat. Acad. Sci. USA 72, 1464 1468 (1975). 

After the initial disclosure of a viable iterative synthetic method for the construction of polyfunctional macromolecules, a small number of articles explored the use of repetitive chemistry for the preparation of dendritic materials. Figure 2.4 illustrates the early branched architectures that were constructed, in most cases, by employing protection-deprotection schemes. Detailed descriptions of the synthetic procedure can be found in Chapters 4 (structures 7-9) and 5 (structures 10 and 11). 

Enzymes are composed of amino acid chains linked via peptide bonds and can be considered as polyfunctional and (multi-)charged macromolecules with a defined, more or less rigid three-dimensional structure. A typical enzyme molecule with a molecular weight of 30,000 Da resembles a compact spherical particle of approx. 4 nm in diameter. Many enzymes, especially those which are regulated by various effectors, consist of more than one amino acid chain (sub-... 

A molecule is called bi- or polyfunctional if two or more reactive or functional groups either are present at the beginning of the reaction or appear in the course of It. A monofunctional material can react at one point, a bifunctional material at two points, and a polyfunctional material at many points. Simple examples of bi- or polyfunctional molei es are hydroxy or amino acids, di- or polyalcohols, -amines, or -acids. These molecules interact with each other through their chemically active groups but since two or more of them are located on each molecule, the reaction continues in two or three directions and linear or tridimensional molecules are formed. Figure 15-1 illustrates schematically the reactimi between two monofunctional molecules, which does not produce macromolecules (a) whereas bifunctional monomers lead to linear-chain molecules (5), and the reaction of trifunctional molecules produces complicated networklike structures (c). 

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