Cycloaliphatic Polymers via Late Transition Metal Catalysis - Late Transition Metal Polymerization Catalysis - page 102

For these reasons relatively little attention is given to ROMP technology in this re-
view.
B. F. Goodrich commercialized a ROMP thermoset material known as Telene ® ,a
liquid reaction molding resin based on the reaction injection molding (RIM) of nor-
bornene-type monomers such as dicyclopentadiene (DCPD). The high degree of
multicyclic monomers in this formulation imparts a high T g to the material (typi-
cally about 150 C). This RIM system takes advantage of B. F. Goodrich proprietary

catalyst and co-catalyst technology [10] to provide a material that has a unique com-
bination of stiffness and toughness. The catalyst systems consist of two components,
one component being dissolved in each of two liquid monomer streams (mainly
DCPD) which are mixed in a mold to give rise to the final composition. The pro-cat-
alyst comprises a long-chain alkylammonium molybdate (the alkyl chains impart
solubility, while the molybdate supplies molybdenum in a non-Lewis acidic form,
preventing carbocationic gelation of the monomer mixture) and the co-catalyst is typ-
ically an ethylaluminum halide species modified (for example with an alkoxy group)
to induce an induction period permitting the mold to be filled prior to the onset of
the exothermic ROMP reaction that gives rise to the final thermoset part. Telene
liquid reaction molding resins and parts are now manufactured and distributed by
Cymetech. Under license to Goodrich, Nippon Zeon commercialized a similar prod-
uct in Japan, using similar catalyst technology, under the name Pentam ® . Virtually
simultaneously Hercules launched a similar product named Metton ® . The Hercules
catalyst technology also applies two component catalysts, a hindered phenoxytung-
sten halide pro-catalyst and a diethylaluminum chloride co-catalyst modified with
a Lewis base or similar additive to impart the desired control over the onset of poly-
merization. The materials are now manufactured and marketed by Metton of Ameri-
ca. Patents have appeared in which ruthenium catalysts are applied for the same
application [11].
In terms of thermoplastic polymers made using ROMP methods the commer-
cial products can be sub-divided, into two categories, based on the glass transition
temperature or melt-processing temperature of the polymer. Early products were
elastomers, the low T g s of which permit processing at low temperatures so that
their unsaturated nature presents no major stability problems. Interestingly Good-
year filed early patents [12] describing a RIM process, using ROMP catalysts, to
produce automobile tires in a mold using cyclopentene as the monomer (but this
novel approach was never commercialized). Although it is possible to obtain high-
er T g thermoplastics based on ROMP chemistry depending on the monomer cho-
sen, hydrogenation of the unsaturated backbone is necessary to afford thermooxi-
dative stability to the polymer [13]. Thus hydrogenation is required, primarily to
allow the high T g polymers to be melt-processed. In the case of the high T g RIM
thermoset materials (above) hydrogenation is clearly not an option; however, in
the case of RIM oxidation this is not a major problem since the polymer is
formed directly as the finished part, and secondly surface oxidation is limited by
the relatively impervious nature of the polymer. In fact a little surface oxidation is
an advantage since it allows the parts to be directly painted without a separate
priming step.