Polycondensation metallocenes

With the details associated with ADMET chemistry reasonably well understood, we have embarked on a study of the synthesis of well-controlled polymer structures via metathesis polycondensation chemistry [37]. A series of well-defined polyolefins have been designed to model the crystallization behavior of polyethylene and its related copolymers, including new materials synthesized by metallocene-based catalysts. This synthesis concept has been reduced to practice, and polymers that will aid in the understanding of branching within polyethylene itself have been produced. 

A generalized electron-counting scheme, known as the mno rule, is applicable to a wide range of polycondensed polyhedral boranes and heteroboranes, metal -laboranes, metallocenes, and any of their combinations. According to this mno rule, the number of electron pairs N necessary for a macropolyhedral system to be stable is... 

A number of organometallic polymers containing metallocenes and metallocene analogues has been well-known for some time2. Because of the features of high-temperature stability and radiation resistance of the ferrocene nucleus, ferrocene-containing polymers are of special interest. Basically, these polymers may be divided into two classes the metallocene moiety is either located in a pendant group or in a backbone of the polymer chain. The former polymers have been synthesized by vinyl polymerization of vinyl metallocene monomers such as vinylferrocene. The latter polymers have been prepared by polycondensation of l,l -disubstituted metallocenes or metallocene dihalides with a.w-disubstituted monomers, and fell into two main types, (A) and (B). 

One of the syntheses of the polymers of type (A) and (B) involves the polycondensation of a metallocene-containing Lewis base or Lewis acid. A number of ferrocene-and cobalticenium-containing Lewis bases have been employed, e.g. ... 

The preparation of polyamides having metallocenes incorporated into the backbone can be achieved by the use of bifunctional ferrocene derivatives, such as diacid chlorides or diamines. In the following, a few examples of such reactions are presented. In the early 1960s Knobloch and Rauscher reported the preparation of polyamides and polyesters by the reaction of 1,1 ferrocenyldicarbonyl chloride 14 with several diamines and diols by interfacial polycondensation.80 The synthesis of elastomeric polyamides 54a, Mn = 10,000-18,000) in high yields was reported by Rausch and co-workers from 1,1 -bis((3-aminoethyl)ferrocene 53 and diacid chlorides (Scheme 12.11). The reaction with bis-isocyanates allows the formation of ferrocene-containing polyureas 54b. 

Metallocene methylene polymers have also been prepared via the preparation of an a-metallocenylcarbocation with an acidic or Lewis acid initiator, followed by polycondensation involving electrophilic substitution of the metallocene nucleus... 

A wide variety of group 4 (Ti, Zr, Hf) metallocene-containing polyethers, polythioethers, polyesters, polyamines, polyoximes, and polyamidoximes has also been reported. Their synthesis, which is based on the polycondensation (with HCl elimination) of CP2MGI2 with difunctional organic species such as diols, dithiols, etc. (Scheme 14), was carried out either in aqueous solution or using interfacial condensation techniques, based upon the... 

There has also been considerable interest directed toward the synthesis of conjugated polymetallocenes due to the electronic communication that these materials may possess. Many polymetallocenes were produced via polycondensation reactions of I,l -disubstituted metallocenes. More rare are examples that describe the polycondensation of 1.3-disubstituted metallocenes. The synthesis of an optically active homoannularly substituted conjugatedpolyferrocene 7 was recently reported by Plenio and coworkers. 

Figure 4. 15) M. Brookhart s new late transition metal systems using Pd and Ni. 16) Ethylene/Propylene copolymers from the work of Wunderlich. 10) J. E. O Gara and K. B. Wagener PE produced by ADMET polycondensation. 13, 14) Kaminsky, Cecchin, and Zucchini s work reviews on metallocene PE catalysis. 11, 12) J. D. Hoffman s equilibrium values derived for an infinitely long PE chain. 9) Work in this study-PE model polymers made by ADMET with precise placement of methyl branches along the backbone.

In the present study Ni ion is being absorbed. The adsorbent species (solid phase) are the three Group IVB products obtained from the interfacial polycondensation reaction between HPIX and the Group IVB metallocene dichlorides " and two commercially available ion exchange resins. Adsorption is the physical or chemical bonding to the surface. 

The polycondensation of acetylene-substituted metallocenes has yielded polymers containing backbone aUcyne bridges. The synthesis of l-iodo-2-methoxy-methyl-3-ethynylferreocene and l-iodo-2-(N,N-dimethylamino methyl)-3-ethynyl-ferreocene was reported by Plenio and coworkers. Polymerization of these ferrocene-based complexes gave rise to soluble bimodal 1,3-linked ferrocene-acetylene polymers. Polymers exhibiting optical activity or functionalized sidechains were produced via Sonogashira coupling reactions. 

The inverse interfacial and aqueous systems are possible because the Group IVB metallocene dichlorides hydrolyze rapidly forming various products. These products are mainly hydroxyl-related and undergo polycondensation in the same manner as the metallocene halides. 

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