Chemical modification of functional

The diverse chemical reactivity of HAs makes them potential toxic compounds, either directly, by chemical modification of functional groups of a variety of biological systems, or indirectly, by their conversion to toxic metabolites. In some cases their metabolites are considered to be toxic in humans, animals and plants even at relatively modest levels of exposure. 

Film-forming biocidal polymers useful in marine antifouling compositions selected from trialkyltin groups chemically bound to homo- and copolymeric chains of organotin acrylate were prepared by various methods such as (1) the polymerization of trialkyltin acrylate or methacrylate monomers, (2) chemical modification of functionalized polymer as P(S-MA) with bis(tributyltm) oxide, (3) grafting or blending of the polymers, e.g., PVC, with trialkyltin acrylate (Scheme 3.23) [262]. 

Soluble es well es cross-linked polymeric reegents heve found numerous epplicetions, namely in the field of organic synthesis, metal chelation or pharmacology. The chemical modification of functional polymers is an important procedure for the preparation of polymeric reagents and has been extensively studied during the last decade. 

Treatments with Chemicals or Resins. Resin treatments are divided into topical or chemical modifications of the fiber itself. Most chemical treatments of synthetic fibers are topical because of the inert character of the fiber itself and the general resistance of the fiber to penetration by reagents. By contrast, ceUulosics and wool possess chemical functionality that makes them reactive with reagents containing groups designed for such purchases. Natural fibers also provide a better substrate for nonreactive topical treatments because they permit better penetration of the reagents. 

Mixed Ether Derivatives of HEC. Several chemical modifications of HEC are commercially available. The secondary substituent is generally of low DS (or MS), and its function is to impart a desirable property lacking in HEC. 

Introduction of heme residues and different artificial receptors in protein molecules in chemical modification of structures and functions of proteins by the cofactor reconstruction method 99Ef0539. 

New elastic polymeric materials (resistance to higher stroke or air) can be obtained by using physical modification methods, but using this method, two phases (PS and rubber) in the mixture were formed. Small rubber particles spread as a PS layer and, after awhile, the relationship between the layers decreases and rubber particles gather in the upper layer of the materials. This can be the cause of the loss of resistance of the materials. These material disadvantages have stimulated the polymer synthesis to increase the PS resistance to higher physico-mechanical properties, such as higher temperature and stroke for the chemical modification of PS with various functional modifiers. 

In the chemical modification of PS with MA, AA, EC, butadiene, and isoprene using cationic catalysis caused either destruction of macromolecules or the binding of functional groups to the aromatic ring. 

The electrophilic functions most commonly used in grafting onto processes are ester 141 144), benzylic halide 145,146) and oxirane, 47). Other functions such as nitrile or anhydride could be used as well. The backbone is a homopolymer (such as PMMA) or a copolymer containing both functionalized and unfunctionalized units. Such species can be obtained either by free radical copolymerization (e.g. styrene-acrylonitrile copolymer) or by partial chemical modification of a homopolymer (e.g. 

Broadening of the optimal pH range for reactive dye biosorption by chemical modification of surface functional groups of Corynebacterium glutamicum biomass... 

Owing to multi-functionahty, physical properties such as solubihty and the glass transition temperature and chemical functionahty the hyperbranched (meth) acrylates can be controlled by the chemical modification of the functional groups. The modifications of the chain architecture and chemical structure by SCV(C)P of inimers and functional monomers, which may lead to a facile, one-pot synthesis of novel functionahzed hyperbranched polymers, is another attractive feature of the process. The procedure can be regarded as a convenient approach toward the preparation of the chemically sensitive interfaces. 

The chemical modification of unsaturated polymers via homogeneous catalytic means offers a potentially useful method for introduction of desirable functional groups on the polymer chains. 

The chemical modification of polymers is a post polymerization process which is used in certain situations i) to improve and optimize the chemical and mechanical properties of existing polymers or ii) to introduce desirable functional groups in a polymer. 

The investigation of the chemical modification of dextran to determine the importance of various reaction parameters that may eventually allow the controlled synthesis of dextran-modified materials has began. The initial parameter chosen was reactant molar ratio, since this reaction variable has previously been found to greatly influence other interfacial condensations. Phase transfer catalysts, PTC s, have been successfully employed in the synthesis of various metal-containing polyethers and polyamines (for instance 26). Thus, the effect of various PTC s was also studied as a function of reactant molar ratio. 

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