Norbornene polymerization

Norbornene polymerization was initiated selectively on the surface of SWCNTs via a specifically adsorbed pyrene-linked ring-opening metathesis polymerization initiator (Fig. 1.20). The adsorption of the organic precursor was followed by cross-metathesis with a ruthenium alkylidene, resulting in a homogeneous noncovalent poly (norbornene) (PNBE) coating [249]. 

Norbornene polymerization CdF Chimie Elf Atochem operated since 1976 Nippon Zeon 2 steps operated since 1991 norbornene norbornene polynorbornene (Norsorex ) hydrogenated norbornene (Zeonex ) RuCls/HCl/BuOH 25-100°C... 

The sheer activity of these new nickel norbornene polymerization catalysts and their very rapid polymerization rates makes them potential catalysts for a new nor-bornene-RIM (reaction injection molding) technology to afford a saturated, oxidatively stable RIM part rather than the unsaturated ROMP (ring-opening metathesis polymerization) polymer that is the current commercial Telene or Metton . Fig. 4.6 illustrates the concept and also exemplifies the very rapid polymerization rates that are observed. 

Fig. 4.6 Typical temperature profile of a bulk norbornene polymerization using naked nickel (early RIM experiment).

Naked nickel (1) is a very effective catalyst for norbornene polymerization. Addition of 1 to 1,2-dichloroethane solutions of norbornene (norbornene Ni molar ratio of 2000 1) gave conversions of norbornene homopolymer typically exceeding 95% after about 1 h. 

Having elucidated fhe end group structure for norbornene polymerized in the presence of ethylene, a catalytic cycle showing initiation, propagation, and chain transfer can be constructed (Fig. 4.14). 

Scheme 4.1 Multi-component catalyst for norbornene polymerization.

The cationic complex, [Ni(Ci2Hi9)]SbF6 can be made independently from Ni(cyclo-l,5-octadiene)2, butadiene, and HSbFg. This material exhibited similarly high activity toward norbornene polymerization. 

Ni(fJ,l r)2. In an effort to lower the molecular weight of the polymer chain and simplify analytical characterization, homopoiymerization of norbornene was carried out in the presence of ethylene pressure. Norbornene polymerizations catalyzed by cationic nickel catalysts such as (// -crotyl)Ni(1,5-fX)l)) ld, are quite susceptible to acyclic olefins as chain transfer agents and produce substantially reduced molecular weight vinyl-terminated poly(norbornenes) (Section 4.2.3.5). 

Exact assignment of the resonances observed in the F, H and "fl NMR spectra of the norbornene oligomers required separation of each member of the series. First, norbornene polymerization with (// -toluene)Ni(C6F5)2 in the presence... 

All of this data suggest strongly that (// -toluene)Ni(C6F5)2 should be thought of as an initiator of norbornene polymerization rather than a catalyst. A full paper describing the chemistry and polymerization performance of this initiator system will be pubhshed shortly [62]. 

Aqueous insertion-type polymerization of norbornene and substituted derivatives [Eq. (7)] has also been investigated. The tolerance of norbornene polymerization using [Pd(NCCH3)4](BF4)2 as an initiator towards added amounts of water was noted by Risse and Mehler in 1992 [91]. 

In 1993, Perez et al. reported norbornene polymerization in aqueous emulsion at 70 °C using PdCl2 as a catalyst precursor [92, 93]. A stable latex consisting of low-molecular-weight oligomeric material (degree of polymerization DP ca. 10) was obtained with low catalyst activities (70 TO h ). Very small latex particles of 10 to 20 nm diameter were reported. In the free radical polymerization of olefinic monomers such small particles are only obtained by microemulsion polymeriza-... 

Adapting the above-mentioned precedents in norbornene polymerization chemistry, the University of Texas research team was able to synthesize cycloaliphatic polymers with pendant-free carboxylic acid groups and carboxylic acids protected with acid-cleaveable groups, such as tert-hvAy esters tailored for 193-nm resist use. They polymerized norbornyl derivatives such as CBN and... 

FIGURE 16.3 Naked -type nickel and palladium catalysts for norbornene polymerization developed by the group at BF Goodrich (M = Ni, Pd). 

FIGURE 16.4 Active species for norbornene polymerization by naked -type nickel catalysts according to Goodall (P = polymer chain). 

SCHEME 16.6 Multicomponent catalysts for norbornene polymerization based on cationic palladium... 

NHC)-Pd complexes and their uses in organic syntheses, ranging from C-C coupling to olefin polymerizations [88]. In this work, different (NHC)-Pd complexes active for co/polymerization of acyclic as well as cychc monomers were discussed, with particular interest in functionalized norbornene polymerizations. 

Complex 2, which is effective for propene polymerization was found to conduct coordination-insertion-type polymerization of norbornene. In Table 3 are shown the effects of cocatalyst in norbornene polymerization with 2 in toluene at 20°C [33,34]. 

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