| 摘要 |
<p>Methods of forming polycycloolefins having high crosslink density are disclosed. Olefins are polymerized via a metathesis mechanism in the presence of a crosslinking agent and a catalyst. The crosslinking agent generally comprises a peroxide that decomposes into reactive species forming crosslinks during post-cure. The catalyst is a ruthenium or osmium carbene complex of general formula (I), wherein M is Os or Ru; R and R1 are independently selected from hydrogen or a hydrocarbon selected from the group consisting of C¿1?-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C2-C20 alkoxycarbonyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy and aryloxy; X and X?1¿ are independently selected from any anionic ligand; and L and L1 are independently selected from any neutral electron donor. Preferably, L and L1 are trialkylphosphine ligands and at least one of the alkyl groups on the phosphine ligand may be a secondary alkyl or cycloalkyl group, especially P(isopropyl)¿3?, P(cyclopentyl)3 and P(cyclohexyl)3. Preferred crosslinking agents are peroxides, such as t-butyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy) hexyne-3, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-di-(tert-butylperoxy) hexane or mixtures thereof. Olefins may be cyclic (e.g., monocyclic, bicyclic or tricyclic) or acyclic. Norbornene or norbornene derivatives are especially preferred.</p> |
