Ceric ion redox initiation systems

To sum up, the optimum conditions for methylmethacrylate grafting onto pulp by the ceric ion redox system can be summarized as follows the grafting is done at 30°C for a 1-h reaction time, using liquor ratio 40 1, acid concentration 1%, initiator concentration 0.1%, and monomer 1 mL/g pulp. 

Mino, G., and S. Kaizerman A new method for the preparation of graft copolymers. Polymerization initiated by ceric ion redox systems. J. Polymer Sci. 31, 242 (1958). 

As a new approach to the preparation of water-soluble polymers in inverse miniemulsions, a redox initiation system consisting of ceric ions and carbohydrate-based surfactant Span 60 as a reducing agent has been successfully used for the... 

A final class of multifunctional initiators is based on the use a (muUi)functional polymer and a low molecular weight redox agent. Radicals on the polymer chain arc generated from the polymer bound functionality by a redox reaction. Ideally, no free initiating species are formed. The best known of this class are the polyol-redox and related systems. Polymers containing hydroxy or glycol and related functionality are subject to one electron oxidation by species such as ceric ions or periodate (Scheme 7.23).266,267 Substrates such as cellulose,... 

The hydroxyl radicals can react with cellulose, initiating graft copolymerization, or react with monomer, resulting in homopolymerization. A similar redox system is based on the use of ceric ions, which produce radicals by direct oxidation of the cellulose chains and thus initiate graft polymerization ... 

This paper summarizes chemical grafting techniques explored in this laboratory that have potential biomedical application. These reactions, initiated by ceric ions, persulfate-bisulfite redox systems, or the presence of comonomers forming donor-acceptor complexes, were carried out in an aqueous environment under conditions which, with suitable modifications, might be tolerated in vivo. Grafting onto tissue surfaces by means of ionizing radiation will not be discussed since techniques for avoiding undesirable side reactions have not yet been developed. 

A number of studies to determine the mechanisms of grafting onto collagen initiated by CAN, including characterization of the reaction products, have been reported (5, 8, 9, 53, 62). Ceric ammonium nitrate forms an effective redox system with alcohols, aldehydes, amines, and thiols. Alcohols form a ceric ion-alcohol complex, and the dissociation of this complex is the rate-determining step 63) ... 

Redox polymerizations are among the most popular techniques for grafting reactions, and of the possible initiator systems, ferrous ion oxidation and those based on ceric ion reduction are widely used. In a redox polymerization, a hydroperoxide or similar group is reduced to a free radical plus an anion, while the metal ion is oxidized to a higher valency state, and at the same time a... 

Since the addition of cerous ions to the ceric sulfate solution suppresses the effect of impurities, Matthews introduced the modified version of this dosimetry system by using a mixture of the ceric and cerous ions (Matthews 1982). Electrochemical potentiometry is applied to evaluate the irradiated solutions by measuring the redox potential difference between the unirradiated and irradiated solutions. This method can be applied in the dose ranges of 0.5-5 kGy or 5-50 kGy depending on the initial ceric ion concentration chosen. An important advantage of this method compared to spectrophotometry is that no dilution of the irradiated solution is needed. 

Only a few of the initiators suitable for polymerizations in aqueous systems have been fully investigated recently described initiators for such systems include new redox combinations, e.g. the ceric ion with thiourea, lithium peroxydiphosphate, and various azo compounds. <... 

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