MODIFICATION OF POLY(METHYLSILENE) CATALYZED BY GROUP-4 AND GROUP-6 TRANSITION-METAL COMPLEXES AND ITS PYROLYSIS

The poly(methylsilene) (1) was modified with the group 4 metallocene C p2MCl2/Red-Al (M = Ti, Zr, Hf) combination catalyst and with the group 6 metal carbonyl M(CO)(6) (M = Cr, Mo, W) catalyst, producing the hig hly cross-linked insoluble polymer and the lowly cross-linked soluble polymer, respectively. An interrelationship between molecular weight a nd percent cermic residue yield with metal within the respective group was not found. The polymers modified with the group 4 metallocene com bination catalysts have higher molecular weight and lower percent cera mic residue yield than the polymers modified with the group 6 metal ca rbonyl catalysts do. The catalytic activity of group 4 metallocene com binations appears to be higher at similar to 100 degrees C, but to be lower at very high temperature than those of group 6 metal carbonyls. The pyrolysis of the modified 1 yielded SiC ceramic.