Polymer Analog Conversions

The configurational equilibrium observed in solution can be displaced when one isomer can be removed from the equilibrium, by, for example, crystallization. For example, when l,4-poly(butadienes) of high trans content are dosed with trace amounts of an a trans poly(butadiene), a decrease in the trans content is initially observed. Subsequently, however, the trans content increases again. It is assumed that a trans isomerization occurs at the crystalline-amorphous interface, whereby the longer trans sequences are incorporated into the crystal lattice and thereby removed from the equilibrium. A new equilibrium is then established by producing more new trans sequences. 

The constitution of the monomeric unit is changed but the degree of polymerization remains constant in polymer analog reactions. Chain analog reactions are a special case where the end groups are transformed but the constitution of the monomeric units is retained. 

An example of a polymer analog reaction is the saponification of poly(methyl methacrylate) to poly(methacrylic acid)  

In industry, polymer analog reactions are carried out on a large scale to produce polymers that cannot be synthesized directly from their monomers. Examples of this are the saponification of poly(vinyl acetate) 

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Polymer-Analogous Conversions of Functional Groups in Polymer Chains... 

This review deals with recent results on the structure and properties of cellulose graft copolymers depending on the structure of cellulose, its pretreatment and the conditions of grafting. Also discussed are polymer-analogous conversions involving grafted chains. 

These data point to the specific behaviour of grafted PS chains in polymer-analogous conversions. As a rule, the functional groups of grafted macromolecules appear to be far more reactive than their homopolymer counterparts. 

The elucidation of the mechanism which accounts for the nitration behaviour of cellulose-PS graft copolymers, particularly the mutual influence of the copolymer components in polymer-analogous conversions, is a problem of great scientific interest. 

The reactions and properties of macromolecules are determined by chemical structure and molecular size. Consequently, it is convenient to use these parameters instead of, for example, mechanisms to classify macro-molecular reactions. Distinction is made among catalyses, isomerizations, polymer analog conversions, chain extension, and degradation reactions according to whether the chemical structure, the molar mass and/or the degree of polymerization are retained or changed. 

Polymer analog conversions differ in a series of characteristic ways from the behavior of the analogous reactions of low-molar-mass compounds. Larger or smaller quantities of side products are produced in every chemical reaction. But with polymers, these side products remain part of the... 

Silicones can be produced either by polymer analog conversions on silicates or by polymerization of low-molar-mass organosilicon compounds. The polymer analog conversion of silicates with hexamethyl disiloxane, isopropanol, and hydrochloric acid at 75° C is successful for some silicates only. The hexamethyl disiloxane is first hydrolyzed to trimethyl silanol ... 

Polymers with metals in the side groups can be produced by polymerization of the corresponding monomers or by polymer analog conversion. For example, vinyl ferrocene copolymerizes to high-molar-mass products with, for example, styrene under the influence of nonoxidizing free radical initiators such as AIBN. BPO oxidizes the iron. 

PPEs should be amenable to postfunctionaUzation schemes. Side chain manipulation of PPEs has been discussed for the case of grafted polymers. Nuyken [126] has shown that a benzylic bromide-functionalized PPE is easily made by the polymer analogous conversion of a benzylic alcohol. This polymer is poised to react with any nucleophile to give side chain functionalized PPEs. Postfunctionalization schemes furnished biotinylated or mannosylated PPEs are useful in sensory schemes (vide infi a) [27,127-131]. 

Preparation of Hf-Containing Polymers Via Polymer-Analogous Conversions (Process I)... 

Polymers with metals in the side groups can be produced by polymerization of the corresponding monomers or by polymer analog conversion. 

Examples of the introduction of metals into polymer chain side groups by polymer analog conversions are the synthesis of poly(p-lithium styrene) [see (3-11)] and the conversion of poly(p-chloromethyl styrene) with sodium tungsten pentacarbonyl ... 

After this, other methods for formation of the gradient of distribution of refractive index were published. Particularly, division in the gravitation field [11], polymer-analogical conversion of polymer films [42], and dipole forced - diffusion of monomers with definite dipole moment into the polymer matrix under influence of inhomogeneous electric field with the given inhomogeneity [43, 44], etc. For some of these methods is not necessary to provide additional manipulation to fix the distribution of refractive index gradient obtained [1]. 

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