Polystyrene from phenyl radicals

Unsubstituted polymer chains cannot form different stereo isomers, while substituted polymers can have a large number of different possible isomeric forms. As a result it is possible to have various configurations for substituted polymers. For example polystyrene produced by radical polymerization is atactic which means the phenyl groups bound to every second C-atom are randomly distributed on both sides of the polymer chain. Polymers produced using Ziegler catalysts, made from monomers like styrene, propene and others are isotactic (Figure 2-2) ... 

The reaction of polystyrene with hydroxyl radicals generated by the photolysis of HjOj in dichloromethane solution occurs by the addition of HO radicals (formed from photolysis of H2O2) to the phenyl ring [2228]. 

Poly(azophenylene-o-carborane) (see 6) has been prepared from diphenyl-o-carborane by means of nitration, reduction, and acylation to initially give 1,2-bis(/ -nitroso-acetylaminophenyl)-o-carborane (NAFC). Rapid decomposition in solution affords phenylene amino phenyl carborane (PAFC) by recombination of phenylene and azophenylene radicals.40 These radicals have also been utilized to form copolymers of carborane-containing copolymers from monomers polymerizable via radical mechanisms. Thus, copolymers of polystyrene and poly(azophenylene) can be readily formed by means of emulsion copolymerization of styrene with NAFC decomposition products. 

Spoly(vinylbenzylchloride). -Cross-linked using divinylbenzene. Chloromethylated, cross-linked polystyrene resins were obtained coiranercielly from Bio-Rad Laboratories. Percent chloromethylation js based on the available phenyl groups in the polymer that is minus the percent cross-linking. =D=dioxane E ethanol. Percent of available chloromethyl croups reacted with donor. —Percent reaction x percent chloromethylation. Polymer prepared by free-radical polymerization of 60.00 para-neta chloromethylated sytrene (Dow Chemical). Reaction heated at 50-55°C. 

Radical fragmentation of 2-nitrophenyl-azo-trityl resin was studied in the presence of various radical acceptor solvents to elucidate possible radical reaction pathways. When using benzene as solvent, only 2-nitro-bi-phenyl was formed as the product of radical substitution reaction (SNR) in 67% yield. Hydrogen-radical abstraction from the polymer backbone (e.g., from the benzylic units of polystyrene) was completely suppressed. When toluene was used as solvent, a mixture of the following products was obtained nitrobenzene, 4-methyl-2 -nitrobisphenyl, 2-methyl-2 -nitro-bisphenyl, and 3-methyl-2 -nitrobisphenyl (9 9 1 1). In the case of toluene, the nitro-aryl radicals undergo H-abstraction with radical substitution as a competing reaction pathway. These results indicate that H-abstraction... 

Figure 10. Phenyl C(1) carbon spectra of radical polystyrene measured In chloroform-d at room temperature (a) and in 1,2-dichlorobenzene at 150 °C (b). Reproduced with permission from Ref. 13. Copyright 1983, John Wiley Sons, Inc.

The main chain scission degradation of polystyrene in CHCI3 is caused by solvent radicals, which abstract hydrogen from polymer molecules. Solvent radicals may be formed by an energy transfer from the excited phenyl groups in polystyrene ... 

Polystyrene is an inexpensive and rigid plastic. Polystyrene is a kind of vinyl polymer. Structurally, it is a long hydrocarbon chain with a phenyl group attached to every other carbon atom. Usually, polystyrene is produced by a radical or anionic polymerization starting from the monomer styrene. These polymers are atactic and amorphous and consequently are not crystallizable. 

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