Cycloaliphatic polyolefins with functional groups were obtained by Pd(II)-catalyzed homo- and copolymerizations of norbornene derivatives. Bicyclo[2.2.1]hept-5-ene-2-carboxylic acid, the corresponding methyl ester, 2-(hydroxymethyl)bicyclo[2.2.1]hept-5-ene, and the corresponding octanoate and decanoate were used as the monomers in these addition polymerizations. Pd(II)−nitrile catalysts [Pd(RCN)4][BF4]2 (with R = CH3 and C2H5) quite selectively polymerized the exo isomers of the esters of 2-(hydroxymethyl)bicyclo[2.2.1]hept-5-ene. Monomer mixtures containing an 80/20 ratio of endo/exo isomers were converted into polymers containing more than 50% of exo units. 1H NMR studies showed that the predominant fraction of the endo isomer remained unreacted. The nitrile based Pd catalysts were not sufficiently active to polymerize the monomers with electron-withdrawing substituents linked to the bicyclic unit at ambient temperature. In-situ prepared (η3-allyl)palladium complexes with associated tetrafluoroborate and hexafluoroantimonate ions were found to be substantially more active. They were able to catalyze the addition polymerization of norbornene derivatives containing a large proportion of endo isomers. Quantitative monomer conversions were achieved for aliphatic esters of 2-(hydroxymethyl)bicyclo[2.2.1]hept-5-ene. Random copolymers of norbornene and the latter esters with molecular weights M n(GPC) above 100 000 were prepared. The (η3-allyl)palladium compounds were suitable for the polymerization of bicyclo[2.2.1]hept-5-ene-2-carboxylic acid methyl ester; high molecular weight materials were obtained via copolymerization with norbornene. Furthermore, addition polymers containing 0.2 carboxylic acid group per repeating unit were prepared by the copolymerization of norbornene and bicyclo[2.2.1]hept-5-ene-2-carboxylic acid. The hexafluoroantimonate-based (η3-allyl)Pd(II) catalyst had a higher polymerization activity than the Pd compound with the smaller BF4 - counterion which was rationalized by a slightly stronger association of BF4 - with the (η3-allyl)Pd(II) unit.

Norbornene derivatives containing ester substituents were submitted to Pd(I1)-catalyzed vinyl addition polymerization. The transition metal catalyst was found to tolerate the ester functionality. However, the rate of polymerization was reduced in comparison to the polymerization of norbornene. The polymerization of the pure exo-isomers produced substantially higher yields than reactions of monomers containing a high proportion of the corresponding endo-isomer. By varying the ester substituent, amorphous polymers with glass transition temperatures over the range of -40 to 268 "C were synthesized. An approximately linear relationship of molecular weight to monomer conversion was established, and the non-uniformity remained narrow (u,/a,, = 1,15-1,25) until high conversions for several of the exo-isomers studied. This indicates that both chain transfer and chain termination are rare. S. Breunig, W. RisseThe present study describes the synthesis of poly(S,6-bicyclo[2.2.l]hept-5-ene)derivatives with ester substituents in position 2. Polymers with appropriate substituents were expected to have good solubility in organic solvents and lower glass transition temperatures than the parent, unsubstituted polymer 3. Results and discussionEsters of bicyclo[2.2. Ilhept-5-ene-2-methanol (4ah) were polymerized by [Pd(CH,CN),] [BF412 in nitromethane at 25 "C, resulting in the corresponding vinyl addition polymers 5a-h (Eq. (1)). In contrast to the vast majority of transition metal catalysts used for insertion polymerizations '), the Pd2+ -based catalyst tolerates the presence of functional groups, such as ester and nitro groups.The polymer yields were only moderate, i.e., in the range of 22-32'4'0, when norbornene derivatives 4a-h with a low exo/endo ratio of 20/80 were used for polymerization (lkb. 1). Predominantly the exo-isomer underwent the polymerization reaction.An increase in molecular weight was observed when higher mole ratios of monomer/Pd(II)-catalyst were used for polymer synthesis; e. g., the molecular weight I % ? " (GPC) of 5 b increased from 5900 to 32000 upon increasing [M]/[I] from 100/1 to 900/1. However, the molecular-weight distributions MW/@,, (in the range of 1,6 to 2,5) were considerably broader than those of the unsubstituted poly(2,3-bicyclo-[2.2.l]hept-2-ene) (3) prepared under similar reaction conditions7).

feri-Butyl-and phenyl-substituted poly(aryl ether ketones) were prepared by a nucleophilic substitution reaction from the corresponding substituted hydroquinones and 4,4'-difluorobenzophenone. Reaction temperatures of 170 °C were sufficient to give high molecular weight poly (oxy-(2-tert-butyl-1,4phenylene)oxy-1,4-phenylenecarbonyl-1,4-phenylene). This polymer was found to be amorphous, Te = 175 °C, and highly soluble in common organic solvents, such as chloroform, THF, and toluene. The tert-butyl substituent was cleaved with trifluoromethanesulfonic acid in a reversed Friedel-Crafts alkylation reaction to produce PEEK (poly(aryl ether ether ketone)). This reaction proceeded to high conversions in the presence of a tert-butyl group acceptor such as toluene.

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