Cyclopentadienyl nickel and palladium complexes/activator system for the vinyl-type copolymerization of norbornene with norbornene carboxylic acid esters: Control of polymer solubility and glass transition temperature

摘要

In non-polar solvents such as toluene, Cp-Ni and -Pd complexes (Cp=eta(5)-C5H5) with appropriate activators have been found to induce the addition polymerization of norbornene in excellent yields, for example (Cp)Pd(allyl)/ [Ph3C][B(C6F5)(4)] gave 105 120 kg-polymer/cat-mol center dot h at room temperature. While the Cp-Pd system was not suitable in the presence of ester-substituted norbornenes, the Cp-Ni system, for example (Cp)Ni(Cl)(PPh3)/AlMe3/B(C6F5)(3) can copolymerize norbomene with 5-norbornene-2-carboxylic acid methyl ester in toluene to give high yields (up to 68% in 2 h at room temperature) of copolymer with variable contents of the methyl ester monomer unit (17.4-60.7 mol-%). These copolymers have high molecular weights ((M) over bar (n)= 234 100-109 500) and narrow molecular weight distributions ((M) over bar (w)/(M) over bar (n)=1.78-1.89). In addition, they are soluble in common organic solvents giving flexible and transparent films on casting, that show very high T-g in the range of 352.8 to 316.0 degrees C. The same Ni-catalyst system can also copolymerize norbomene derivatives with bulky substituents, i.e., 2-butyl-5-norbornene and 5-norborene-2-carboxylic acid butyl ester. The T-g of these copolymers 1 are lower (294.9-267.3 degrees C) than the methyl ester-based copolymers, demonstrating that the T-g of the polynorbornene copolymer film can be tailored simply by changing the alkyl group of the monomer to within the range of 352 to 267 degrees C.