Selenium polymers

Kajiwara,M and Miwam A. (1982) Polymerization of hexachlorocyclo-triphosphazene by sulphur and selenium. Polymer, 23, 495. 

Diselenium dichloride acts as a solvent for selenium. Similarly disulphur dichloride is a solvent for sulphur and also many other covalent compounds, such as iodine. S Clj attacks rubber in such a way that sulphur atoms are introduced into the polymer chains of the rubber, so hardening it. This product is known as vulcanised rubber. The structure of these dichlorides is given below ... 

Zinc—bromine storage batteries (qv) are under development as load-leveling devices in electric utilities (64). Photovoltaic batteries have been made of selenium or boron doped with bromine. Graphite fibers and certain polymers can be made electrically conductive by being doped with bromine. Bromine is used in quartz—haUde light bulbs. Bromine is used to etch aluminum, copper, and semi-conductors. Bromine and its salts are known to recover gold and other precious metals from their ores. Bromine can be used to desulfurize fine coal (see Coal conversion processes). Table 5 shows estimates of the primary uses of bromine. 

A number of examples have been studied in recent years, including liquid sulfur [1-3,8] and selenium [4], poly(o -methylstyrene) [5-7], polymer-like micelles [9,11], and protein filaments [12]. Besides their importance for applications, EP pose a number of basic questions concerning phase transformations, conformational and relaxational properties, dynamics, etc. which distinguish them from conventional dead polymers in which the reaction of polymerization has been terminated. EP motivate intensive research activity in this field at present. 

N. Burford, j. Passmore and J. C. P. Sanders, Chap. 2, Preparation, Structure and Energetics of the Homopoly-atomic Cations of Groups 16 and 17, in J. F. Liebman and A. Greenburg (eds.). From Atoms to Polymers Isoelec-tronic Analogies, VCH PubL, Honda, 1989, pp. 53-108. J. Passmore, Chap. 19 Homopolyatomic Selenium Cations... 

As discussed earlier the whole process is a redox reaction. Selenium is reduced using sodium borohydride to give selenide ions. In the above reaction, the metal ion reacts with the polymer (PVP or PVA) solution to form the polymer-metal ion solution. Addition of the selenide ion solution to the polymer-metal ion solutions resulted in instantaneous change in the colour of the solutions from colourless to orange (PVA) and orange red (PVP). This indicates the formation of CdSe nanoparticles. The addition of the selenide solution to the polymer - metal ion solution resulted in gradual release of selenide ion (Se -) upon hydrolytic decomposition in alkaline media (equation 4). The released selenide ions then react with metal ion to form seed particles (nucleation). 

Amorphous phase, of polymers, 20 400 Amorphous polymers, 10 203 crystallization of, 19 844 Amorphous red selenium, 22 74 Amorphous regions, in fibers, 11 171 Amorphous resins, use in thermoforming, 19 555... 

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