Polypentenamer

Pentenamer Ionomers. Unsaturated polypentenamer elastomers have been derivatized by post-synthesis reactions (72—74). Phosphonate, thioglycolate, sulfonate, and carboxylate derivatives have been prepared and converted into ionomers. 

Unsubstituted monocyclic mono-olefins, e.g. cyclopentene and cyclo-octene, which yield polypentenamers and polyoctenamers respectively. 

Of these various groups there was extensive interest for some years in polyalkenamers such as frani -polypentenamer which has now abated whilst interest in polynorbomene is steadily increasing. Since the chemistry and technology of the two types is somewhat different each type will be dealt with separately. A third group comprises the chlorine-containing polymers announced by Goodyear in 1980. 

The polyalkenamers are usually prepared by means of a Ziegler-Natta catalyst system. For example fran.v-polypentenamer may be obtained from cyclopentene... 

As a class the aliphatic polyalkenamers have low values due to a combination of low chain stiffness and low interchain attraction. The presence of double bonds has the effect of increasing the flexibility of adjacent single bonds (see Chapter 4) and overall this leads to a reduction in. Thus in the sequence from polydecenamer down to polypentenamer an increase in the double bond concentration leads to a lowering of Tg. On the other hand the Tg of polybutenamer, i.e. poly butadiene, is somewhat higher than that of polypentenamer, presumably because the proportion of stiff links, i.e. double bonds, becomes sufficiently high to override the flexibilising effect on adjacent chains. Consequently the polypentenamers have the lowest Tg values known for hydrocarbon polymers (cis- -114°C, trans- -97°C). 

The crystallinity is more persistent for the polypentena-mer over the same increments of comonomer or 1,5-cyclooctadiene introduction. The crystalline melting point is 8°C for the polypentenamer, 2°, -2°, and -8°C at 5, 10 and 15% comonomer (1,5-cyclooctadiene), respectively, from Table III and -13°C at 25% comonomer from Table II. The position of the crystallization temperature during the heating cycle moves upward from -69°C for polypentenamer, to -65°C at 10% comonomer, to -61°C at 15% and -55°C at 25% comonomer. 

This hypothesis is supported by Chauvin s report (33) on a catalyst derived from (CO)5W=C(OEt)C4H9. This highly stable carbene-W(O) compound does not display catalytic activity for cyclopentene monomer. When mixed in the dark with TiCl4, a slow evolution of 1 equivalent of CO occurs. Subsequent thermal or photochemical activation produces ah extremely efficient catalyst system. Chauvin demonstrated that a high conversion to polypentenamer is obtainable at a W/cyclopentene ratio of 10 li at 5°C. The role of TiCI4 is not well understood nevertheless, it promotes carbonyl displacement which appears to be essential. 

This PSH technique was later utilized as an effective method of reductive modification for the unsaturated polymers such as polydiene rubbers and polypentenamer by Mango (2) and Samui et al ( ) ... 

The quantitative use of high resolution solution spectra for the determination of configuration has also been ably demonstrated for other elastomer systems such as polypentenamer (23,24,25), polybutadiene (26, ), and polyisoprene (1 ). One would like to explore the possibilities of analyzing solid elastomer systems in terms of high resolution spectral discrimination. 

Cycloalkenes undergo ring-opening polymerization in the presence of coordination initiators based on transition metals to yield polymers containing a double bond, for instance, cyclo-pentene yields polypentenamer [IUPAC poly(pent-l-ene-l,5-diyl)] [Amass, 1989 Cazalis et al., 2000, 2002a,b Claverie and Soula, 2003 Doherty et al., 1986 Ivin, 1984, 1987 Ivin and Mol, 1997 Ofstead, 1988 Schrock, 1990, 1994 Tmka and Gmbbs, 2001], The... 

BR, polybutadiene SBR, polyfstyrene-co-1,4-butadiene NBR, poly(acrylonitrile-co-l,4-butadiene) PP, polypentenamer IR, polyisoprene. 

Whereas only limited stereoselectivity is characteristic of the metathesis of acyclic olefins, ring-opening metathesis polymerization of cycloalkenes may be highly stereoselective provided the proper catalysts and reaction conditions are selected. Cyclopentene, for instance, is transformed to either all-cis [Eq. (12.25)] or all-frans polypentenamers [Eq. (12.26)] in the presence of tungsten catalysts 21 92... 

Sanui and co-workers [67] carried out hydroformylation of polypentenamer (PPA). They converted hydroformyl group of the modified PPA to the aldoxime and subsequently to nitrile derivatives (Scheme 4.5). Then they carried out hydrogenation to convert the amorphous, unsaturated nitrile derivative to the crystalline saturated polymer. 

Tabelle 1 gibt einen Uberblick iiber von G. Natta und G. Dall Asta erhaltene kristalline bzw. kristallisierbare Polyalkenamere mit uber-wiegender trans-Struktur 122>. Nur vom Polypentenamer ist bisher auch das reine cis-Isomer beschrieben worden. 

It is part of a homologous series of linear unsaturated polymers that are termed polyalkenamers. Polypentenamer is an interesting member of this series because cyclopentcne is economically available from petrochemical by-products and because the polymer is a readily vulcanizable elastomer (since it contains residual C—C double bonds cf. p. 10). 

The speed and efficiency of chain growth relative to termination of the metathesis catalysts provides high molecular weight polymers. Different catalyst mixtures produce different double bond geometries and tacticities. These factors have been studied in detail since one of the first promising polymers produced by ROMP was polypentenamer. The all-trans isomer is an elastomer and was studied as an excellent material for tire manufacture, while the cis isomer is a nonelastomeric solid (equation 11). ... 

Kranz and Beck [268] have calculated that the enthalpies of polymerization of liquid cyclopentene to solid cis and trans polypentenamer are 4.2 and 3.2 kcal mole", in good agreement with a calorimetric value of 4.5 kcal mole for a 65% trans polymer. Other than this limited thermodynamic data the quantitative aspects of the polymerization are unknown of particular interest would be the factors influencing molecular weight and molecular weight distribution. 

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