Polymerization of Olefin-Functionalized Metallocenes

Shortly after the first synthesis of ferrocene by Kealy and Pauson, Arimoto and Haven reported the homopolymerization and copolymerization of vinylferrocene. 

The organometallic polymer shown in scheme 3 was synthesized using phosphoric acid, persulfate, or azobisisobutyronitrile (AIBN) as catalyst. Copolymers prepared with methyl methacrylate, styrene, and chloroprene as well as the homopolymer were crosslinked with formaldehyde. These polymers rmderwent reversible chemical oxidation with ceric sulfate. 

Pittman and coworkers reported a number of ferrocene-functionalized polymers in the 1960s and 1970s that not only included the synthesis but also the properties of these polymers. In particular, the bulk and solution polymerization of vinylferrocene along with the physical, chemical, and electrical properties of many polymers and copolymers were studied. The copolymerization of vinyl-ferrocene with styrene was reported by Frey and co-workers in 1999, using living radical initiator 2,2,6,6-tetramethyl-l-pyperidinyl-l-oxy (TEMPO). The polymers obtained by this method were block copolymers with narrow polydis-persities. 

There have also been many studies of the polymerization kinetics of organoiron monomers these have shown that such polymerizations often do not follow the same rate laws as organic monomers. Ferrocene-substituted polymethacrylates possessing nonlinear optical (NLO) properties were reported by Wright and coworkers. The copolymerization of the ferrocenyl-fimctionalized monomer (5mol%) 14 with methyl methacrylate 15 yielded the organometaUic polymer 16, as shown in scheme 4. This polymer displayed second-harmonic-generation activity and possessed 

A method for the preparation of ferrocene-functionalized acrylate and methacrylate monomers as well as their homopolymerization and copolymerization leactions was repeated in 2002. Using AIBN as a radical initiator, polyferro-cenylethyl acrylate, methacrylate, acrylamide, and methacrylamide were synthesized, as shown in scheme 5. 

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