Lanthanide metal-organic frameworks as ziegler–natta catalysts for the selective polymerization of isoprene

The unprecedented ability of neodymium-based metal organic frameworks (MOFs) aspolymerisation pre-catalysts towards isoprene is reported. Combined with methylaluminoxane(MAO) or modified MAO (MMAO), they afford mainly cis-selective polyisoprene, up to90.7%. Both the activity and the selectivity are tentatively ascribed to the intrinsic microstructureof the starting materials. Compared to conventional carboxylates, MOFs associatedto an Al co-catalyst are less active but the selectivity is found to be higher, and itmay be modified by controlling the access to the pores, which would be favored at highertemperatures. Some residual crystallineMOF remains disseminated within thepolymer matrix, as shown by X-raydiffraction and X-ray absorption spectroscopystudies