Free radical polymerization, ferrocenes

For free radical polymerization reactions, the initiating radicals must be generated from azo-initiators because peroxides cause oxidation of the metal. In polymerizations of the type shown in reaction (2) the side group ferrocene units are the source of both the... 

Other ferrocene pendant-containing polymers include polymers such as poly(ferrocenyl methyl acrylate) and poly(ferrocenyl methyl methacrylate) [23]. These polymers have been prepared from the free-radical polymerization of the corresponding ferrocenyl acrylate monomers (Fig. 8.3) [23]. 

Photoinitiators which form with a co-initiator, a charge-transfer complex (CT), and further dissociate into radicals, which initiate free radical polymerization. To this group belong, for example, ferrocene (photoinitiator) and carbon tetrachloride (co-initiator) (cf section 5.8). 

The earliest routes to polyferrocenylene involved poorly defined free-radical recombination processes (Eq. 3.1). In 1960, the polymerization of molten ferrocene at 200 °C in the presence of approximately stoichiometric amounts of t-butyl peroxide, t-BuOOt-Bu, as the radical source was described [12-14]. The yields of soluble material of idealized structure 3.4 were low (ca. 5-15%), as were the molecular weights (<7000). 

Polymers with metals in the side groups can be produced by polymerization of the corresponding monomers or by polymer analog conversion. For example, vinyl ferrocene copolymerizes to high-molar-mass products with, for example, styrene under the influence of nonoxidizing free radical initiators such as AIBN. BPO oxidizes the iron. 

Synthesis of poly(l,r-ferrocenylene) (2) has been carried out by various methods based on the established coupling reactions of benzene derivatives. The earliest study by Korshak et al. [27-9] used step-growth polymerization of ferrocene via free-radical intermediates generated with radical sources such as t-butyl peroxide at elevated temperatures. This method, how-... 

Polymerization of organoiron monomers has also resulted in the production of liquid crystalline polymers containing ferrocene units in their sidechains. " Scheme 6 illustrates Deschenaux s free-radical synthesis of ferrocene functionalized thermotropic liquid crystalline polymethacrylates Monomer 31 and its corresponding polymer 32 exhibited enantiotropic smectic A and C phases. 

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