Metal monomers, copolymerization

The field of metal-catalyzed copolymerization of oxetanes and C02 will continue to flourish, due not only to the versatility of the reaction but also to the aliphatic polycarbonate products being important components of thermoplastic elastomers that, in turn, have huge potential in medical applications such as sutures, drug-delivery systems, body, and dental implants, and tissue engineering. The exploration of other oxetane monomers (Figure 8.17) such as 3,3-dimethyloxetane and 3-methoxymethyl-3-methyloxetane, will surely provide a multitude of applications... 

The second type includes a functionalized monomer copolymerized with styrene and DVB. For example, j)-bromostyrene may be included in the reaction mixture to provide the desired concentration of functional groups in the support. These groups may eventually be converted into phosphines by reaction with lithium diphenylphosphide. Such resins with low phosphine concentrations are the supports of choice for attachment of monophosphine-substituted metal clusters because the ligands are sparsely and almost randomly distributed in the polymers (5). 

The addition of acrylates to the feed is not without some negative consequences. As the amount of acrylate is increased from 1 to 12 mol %, the catalyst turnover numbers decrease from 7710 mol of ethyl-ene/mol of catalyst to 455 and the molecular weight drops from ca. 88 000 to 11 000. The decreased rates are thought to be due to the formation of chelated species, E, involving dative bonding that blocks the needed coordination site. Nevertheless, this is a substantial step forward in the metal-catalyzed copolymerization field as it is the first report of a metal-catalyzed copolymerization of ethylene and acrylate monomers that yields high molecular weight polymer. 

Gupta and Neckers (99) used another complexing monomer. They copolymerTzed 4-methyl-4-vinyl-2,2 -bipyridine with divinylbenzene in the presence of metal ions Ni, Co " ", and Cu . After removing the metal, the polymers retained some memory of the original chelating metal. Braun and Kuchen (100) changed the procedure somewhat since they prepared and characterized the metal-monomer complex before polymerization. They used bis [bis (4-vinylphenyl)dithiophosphinato]nickel(II) and cobalt(II) and copolymerized these to macroporous polymers. After removal of the metal ions the nickel polymer showed an uptake ratio of nickel cobalt of 1.4 and the cobalt polymer of cobalt nickel of 2.4. 

In this chapter, we have summarized three different strategies to use phosphonated copolymers as corrosion inhibitors to protect metals. In the first part, the blends of organophosphorus monomers copolymerized with MMA in a PVDF matrix showed relatively good efficiency. These studies also showed phosphonic acid groups as good adhesion/corrosion promoters, but... 

All of these interesting features of the model organometallic monomer raised questions about other n -vinylcyclopentadienyl-transition metal monomers. Could they be synthesized, polymerized, or copolymerized To that end, (n -vinylcyclopentadienyl)tricarbonyl-manganese, 4.(q vinylcyclopentadienyl)dicarbonylnitrosyl-chromium, and 3—vinvl bis f nival anadi iron. war a nr ana... 

Since was stable to free radical polymerization conditions, copolymerizations with styrene (M2) were carried out to ascertain the reactivity ratios and the e value for comparison to the other (n vinylcyclopentadienyl)-metal monomers 1, 4, 18, and 22. 

Several new and general synthetic routes to vinyl organo-metallic monomers have been developed in our laboratories. Many of these monomers undergo radical-initiated homo- and copolymerizations to produce a variety of new metal-containing polymers. 

Direct copolymerization of aromatic a-olefins and borane-containing monomers with early tmnsitlon metal catalysts Beside the early transition metal-catalyzed copolymerization of aliphatic a-olefins with borane-containing monomers. 

In contrast to the above-mentioned monomers, fundamental polar vinyl monomers, whose polar group is directly attached to the olefin moiety, are difficult to be copolymerized with CO. Among many problems associated with metal-catalyzed copolymerization of polar vinyl monomers with CO, the most critical one is the formation of chelate intermediates after the... 

Small amounts of specially functionalized monomers are often copolymerized with acryUc monomers in order to modify or improve the properties of the polymer. These functional monomers can bring about improvements either directiy or by providing sites for further reaction with metal ions, cross-linkers, or other compounds and resins. Table 9 Hsts some of the more common functional monomers used in the preparation of acryUc copolymers. 

GopolymeriZation Initiators. The copolymerization of styrene and dienes in hydrocarbon solution with alkyUithium initiators produces a tapered block copolymer stmcture because of the large differences in monomer reactivity ratios for styrene (r < 0.1) and dienes (r > 10) (1,33,34). In order to obtain random copolymers of styrene and dienes, it is necessary to either add small amounts of a Lewis base such as tetrahydrofuran or an alkaU metal alkoxide (MtOR, where Mt = Na, K, Rb, or Cs). In contrast to Lewis bases which promote formation of undesirable vinyl microstmcture in diene polymerizations (57), the addition of small amounts of an alkaU metal alkoxide such as potassium amyloxide ([ROK]/[Li] = 0.08) is sufficient to promote random copolymerization of styrene and diene without producing significant increases in the amount of vinyl microstmcture (58,59). 

The reactions of alkyl hydroperoxides with ferrous ion (eq. 11) generate alkoxy radicals. These free-radical initiator systems are used industrially for the emulsion polymerization and copolymerization of vinyl monomers, eg, butadiene—styrene. The use of hydroperoxides in the presence of transition-metal ions to synthesize a large variety of products has been reviewed (48,51). 

There have been other approaches to obtaining rubber/metal adhesion besides primers or additives consisting of phenolics or epoxies plus halogenated elastomers. For example, carboxylated polymers (olefins and diolefins copolymerized with acrylic acid monomers) have shown excellent adhesion to metals. Very little carboxyl is necessary, and polymers with carboxyl contents as low as 0.1% show good adhesion when laminated to bare steel. When these materials possess... 

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