Reactivity of polymers

Homogeneous GopolymeriZation. Nearly all acryhc fibers are made from acrylonitrile copolymers containing one or more additional monomers that modify the properties of the fiber. Thus copolymerization kinetics is a key technical area in the acryhc fiber industry. When carried out in a homogeneous solution, the copolymerization of acrylonitrile foUows the normal kinetic rate laws of copolymerization. Comprehensive treatments of this general subject have been pubhshed (35—39). The more specific subject of acrylonitrile copolymerization has been reviewed (40). The general subject of the reactivity of polymer radicals has been treated in depth (41). 

The ratio describes the relative reactivity of polymer chain M toward monomer M and monomer M2. Likewise, describes the relative reactivity of polymer chain M2 toward M2 and M. With a steady-state assumption, the copolymerisation equation can be derived from the propagation steps in equations 3—6. 

There are two strategies for constructing a polymer with benzyl ester in the middle of the skeleton. One is to make polymer skeletons with the same molecular weight, and then combine two skeletons with benzyl ester. The other is to synthesize a chemical with propagation sites of polymerization at both sides of benzyl ester, and use the chemical as an initiator of living polymerization. Since the former strategy did not work well, probably due to low reactivity of polymer molecules with benzyl esters, the latter approach will be mentioned. 

This point of view concerning the mechanism of mechanochemical destruction of macromolecular compounds is based on two factors. One is the gradual character of this process, as reported by us earlier (JO). The other factor is the increase in potential energy and, consequently, the chemical reactivity of polymer systems that are placed in a stressed state mechanically. 

Protocol for Oxidation with and Reactivation of Polymer-Supported Periodinane26... 

The reactivity of polymers containing unsaturations has also been extensively studied in terms of reactivity and structures [91, 92]. 

Rimmer [118] and Caffetera [119] focused their studies on the reactivity of polymers bearing double bonds in order to synthesize macroinitiators able to give block copolymers. These authors copolymerized monomers such as methyl methacrylate (MMA) or styrene (St) with 2-3 dimethyl butadiene giving copolymers presenting the structure shown in Scheme 36 with... 

Some authors took advantage of the reactivity of polymers with ozone to recycle some peculiar plastic wastes coming from different origins. In this way, Fargere [155, 156] succeeded in degradation of cross-linked ethylene-vinyl acetate copolymers used in the production of sport shoes. This operation was achieved on grinded industrial wastes in suspension in CC14. In a second... 

Figure 13 Temperature dependence of the photochemical reactivity of polymer, 30b. The change in absorbance after 0.5 min of irradiation (A0-AQ5) of the C=C stretching band relative to the initial absorbance (A0) was used to monitor reactivity. (Reprinted with permission from Gangadhara and Kishore [64]. Copyright 1993 American Chemical Society.)...

STRUCTURE AND REACTIVITY OF POLYMER-SUPPORTED CARBONYLATION CATALYSTS... 

Structure and Reactivity of Polymer-supported Carbonylation Catalysts... 

In the study of anionic copolymerization it is possible to use two types of approach. The first method is the use of the classical copolymer composition equations developed for free radical polymerization. The second is unique to anionic polymerization and depends on the fact that for living systems it is possible to prepare an active polymer of one monomer and to study its reaction with the second monomer. The initial rate of disappearance of one type of active end, or the appearance of the other type (usually determined spectroscopically) or the rate of monomer consumption gives directly the reactivity of polymer-1 with monomer-2. It is in principle possible to compare the two methods to see if additional complications occur when both monomers are present together. 

Polymers are substances of high molecular weight made up of repeating monomer units. Substances with short chains containing relatively few monomers are called oligomers. Polymers owe their unique properties to their size, their three-dimensional shape and sometimes to their asymmetry. The chemical reactivity of polymers depends on the chemistry of their monomer units, but their properties depend to a large extent on the way the monomers are put together it is this fact that leads to the versatility of synthetic polymers. 

We have investigated the solvolytic stability and reactivity of polymer-bound borohydrides and have evaluated these materials in several applications such as solvent purification, arsine generation, and metal reduction. These polymer-bound borohydrides offer several advantages over sodium or tetraethylammonium borohydride. The primary advantages are the convenience of use and the minimal introduction of ionic species or organic by-products into the treated bulk media. With the polymer-bound borohydrides, the cation is bonded covalently to the insoluble resin while the borohydride anion or its oxidation product (borate) is retained by ionic bonding. Typically, boron at levels of less than 5 ppm is the only impurity introduced into the treated medium. 

D.T. Clark. Structure, Bonding, and Reactivity of Polymer Surfaces Studies by Means of ESCA. In R. Vanselow, editor. Chemistry and Physics of Solid Surfaces, Volume 2. CRC Press, Boca Raton, FL, 1979. 

Another factor which affects the reactivity of polymer molecules is that the reactants must be expected to achieve a particular geometrical relationship with respect to each other in order to form the excited complex from which reaction occurs. If mobility is severely restricted, this geometry may not be achievable within the lifetime of the excitation, and chemists not familiar with macromolecular reactions might assume that the restrictions of motion in the solid state would be so great that reaction would not occur at all. In fact, this is not the case, and there are many examples of photochemical reactions which are just as efficient in solid polymers as they are in dilute solutions of small-... 

H. Liang, X. Li, Visible-induced photocatal34ic reactivity of polymer-sensitized titania nanotube films . Applied Catalysis B Environmental, 86, 8-17, (2009). 

The mechanism of polyoondensation reactions is thought to parallel that of the low-molecular-weight analogs. As a result of their macromolecular nature, polymers would be expected to have retarded mobility. It was therefore predicted, purely on theoretical arguments, that the chemical reactivity of polymers should be low. 

Berlin, A. A. Sayadyan, A. A. Enikolopyan, N. S. Molecular-weight distribution and reactivity of polymers in concentrated and diluted solutions. VisokoMolekul. Soedin-A, 1969,11,1893. 

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