Robert Sydney Kenyon

Acid Enhancement Effects in the Radiation Grafting of Monomers to Polyethylene and the Use of These Copolymers for Enzyme Immobilization and Related Reactions

Abstract The use of mineral acid to enhance the radiation grafting of monomers to trunk polymers such as polyethylene is shown to be of value for the insolubilization of enzymes and the hetero-genization of catalytically active homogeneous complexes. Two general methods are described showing how acid enhancement effects can be used in the immobilization reactions. In the first technique, styrene is grafted, and the resulting co-polymer can be nitrated followed by subsequent chemical reactions to yield an appropriate substituent to which the attach ment processes can occur. Alternatively, p-nitrostyrene can be grafted directly. In the latter method, the acid enhancement is shown to be valuable, since the monomer is deactivating in radiation grafting and any technique for improving yields is useful. The acid enhancement effect is also shown to be of value for grafting to polyethylene, since this backbone polymer is less susceptible to grafting than the other two trunk polymers studied, i. e., polypropylene ...

Radiation-Induced Reactions with Cellulose. XI. Comparison of Cellulose with Wool and Polyethylene as Trunk Polymers in Copolymerization

Abstract The effect of structure of trunk polymer on radiation co-polymerization has been studied using cellulose, polyethylene, and wool as representative systems. Styrene, 4-vinylpyridine, and 5-methyl-2-vinylpyridine were used as monomers in a range of polar solvents. All grafting experiments were by the simultaneous method. For styrene in methanol system, cellu-lose and polyethylene exhibited Trommsdorff effects whereas wool did not. For the vinylpyridine monomers, gel effects were observed with both cellulose and wool. The results have been interpreted in terms of a charge-transfer theory for grafting.

Enzyme immobilization by covalent attachment to novel polymer matrices prepared by a radiation grafting technique

By an irradiation process, p-nitrostyrene has been surface grafted onto a representative trunk polymer, polypropylene; conversion of the NO2 substituent into a suitable functional group (–NCS) gives a water-insoluble matrix to which enzymes may be covalently bound whilst retaining enzymic activity.

Mechanistic studies of the hydrogen isotope exchange reaction catalysed by homogeneous platinum salts

Deuterium exchange between D2O–CH3CO2D solvent and a variety of aromatic compounds is catalysed by tetrachloroplatinate(II) ions. Rhodium and iridium salts are also shown to be homogeneous catalysts for these reactions. Multiple exchange is a consistent phenomenon of all systems. Conditions influencing the stability of platinum(II) in solution are discussed in detail and the basis for the very careful distinction between homogeneous catalysed exchange and the possibility of accompanying heterogeneous exchange by colloidal Pt0 is delineated. The exchange kinetics with benzene show inverse first-order dependence on Cl–. A complicated acid dependence on the reaction is found and interpreted in terms of the effect of acid on the stability of the platinum(II) in solution. These kinetic results are shown to be consistent with the predominant participation of a dissociative π-complex mechanism for the exchange process. The possible relevance of reaction intermediates proposed by other workers is also discussed.