Reaction Injection Molding RIM of Norbomenes

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. 

Catalyst 1, [(z7 -crotyl)(cycloocta-l,5-diene)nickel]hexafluorophosphate ( naked nickel ), was prepared following a procedure developed for the methallyl isomer by Tkatchenko and coworkers [35, 37]. Thus bis(cyclo-l,5-octadiene)nickel was reacted with crotyl bromide to yield the bromide-bridged (// -crotyl)nickel dimer. Abstraction of the bromide by thallium hexafluorophosphate in the presence of cyclo-1,5-octadiene yielded 1. The structure of 1 in solution is consistent with its solid state X-ray crystal structure [38]. 

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. 

A series of homopolymerizations of norbornene and copolymerizations of norbornene and 5-decyhiorbornene were carried out at a 4000 1 monomer to catalyst ratio using catalyst 1. The polymerizations were conducted at room temperature for 1 h before short stopping the reaction. The results of these runs are presented in Tab. 4.1. 

The conversions of monomer to polymer were excellent. It should be pointed out that while the reactions were typically run for an hour, it was clear that the monomer was very highly converted within the first couple of minutes (indeed, as mentioned above, the very first reaction resulted in high conversion of 2000 moles of norbornene within 3 si). 

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