CHEMICAL MODIFICATIONS OF RUBBERS BY METATHESIS CATALYSTS

Metathesis catalysts are very unique catalyst systems composed of WCl6 or MoCl5 (in most cases) and organometalic compounds (in many cases, Sn(CH3)4 or Al(C2H5)2Cl). They are reactive towards olefinic compounds, and rearrangements of the double bonds occur. The metathesis reactions are classified into (i) olefin metathesis, (ii) metathesis polymerization, and (iii) metathesis degradation. Olefin metathesis and metathesis polymerization are briefly reviewed. From a view point of polymer reactions, several articles treating metathesis degradation were extensively reviewed. In these studies, rubbers, i.e., natural rubber, cis-1, 4-polyisoprene, polybutadienes, styrene-butadiene rubber, polyalkenamers were the substrates of the reaction. It is suggested that this reaction may be useful not only in degradation of rubbers, but also in some chemical modifications, for example, synthesis of reactive oligomers, syntheses of graft and block copolymers.