Supported neodymium catalysts for isoprene and rac-ß-butyrolactone polymerization: modulation of reactivity by controlled grafting.

A series of hybrid materials, bearing neodymium silylamide initiating groups, have been shown to mediate isoprene polymerization when combined with alkyl aluminum activators [methylaluminoxane, AlEt(2)Cl, Al(iBu)(3)]. The surface species nature and relative distribution were correlated with isoprene polymerization activity and selectivity. This approach to stereocontrol modulation has been extended to racemic ß-butyrolactone isoselective ring opening polymerization.