Polymerization suicide

Formation of block polymers is not limited to hydrocarbon monomers only. For example, living polystyrene initiates polymerization of methyl methacrylate and a block polymer of polystyrene and of polymethyl methacrylate results.34 However, methyl methacrylate represents a class of monomers which may be named a suicide monomer. Its polymerization can be initiated by carbanions or by an electron transfer process, the propagation reaction is rapid but eventually termination takes place. Presumably, the reactive carbanion interacts with the methyl group of the ester according to the following reaction... 

Styrene polymerization, 175 Suicide monomer, 180 Sulfur dioxide clathrate, 2 in hydroquinone, 7... 

However, an important problem arises during the peroxidative removal of phenols from aqueous solutions PX is inactivated by free radicals, as well as by oligomeric and polymeric products formed in the reaction, which attach themselves to the enzyme (Nazari and others 2007). This suicide peroxide inactivation has been shown to reduce the sensitivity and efficiency of PX. Several techniques have been introduced to reduce the extent of suicide inactivation and to improve the lifetime of the active enzyme, such as immobilization. Moreover, Nazari and others (2007) reported a mechanism to prevent and control the suicide peroxide inactivation of horseradish PX by means of the activation and stabilization effects of Ni2+ ion, which was found to be useful in processes such as phenol removal and peroxidative conversion of reducing substrates, in which a high concentration of hydrogen peroxide may lead to irreversible enzyme inactivation. 

Termination by reaction with monomer or polymer is a kind of suicide of the growing polymer. A hydride transfer occurs in the cationic polymerization of propylene. The ally lie groupings are resonance stabilized and do not add on any more propylene ... 

A suicide also occurs if the atom carrying the cation in the polymer is more basic than the same atom in the monomer, and in this case it occurs by transfer to polymer. An example of this is the polymerization of thietanes with (C2H5)30 BFf,... 

If termination by the monomer or the polymer occurs, this is known as suicide of the polymer. In the polymerization of propylene by typical cationic initiators (that is, in the absence of a polyinsertion mechanism), a hydride shift, for example, can occur ... 

Much of what we will describe in this section is based on the pioneering work of Flory, who earned the 1974 Nobel Prize in Chemistry for his work in polymer chemistry. Flory was hired by DuPont in 1934, where he was assigned to the labs of Carothers. The brilliant Caro-thers is certainly one of the fathers of pol)nner chemistry, and his DuPont labs first produced neoprene, polyesters, and nylon, among others. Carothers would have certainly earned a Nobel Prize himself, but he committed suicide in 1937 at the age of 41. Beginning in the environment that created modern polymer science and later in an academic career, Flory devel-of>ed the foundations of the physical organic chemistry of polymerization. 

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