CATALYTIC PROPERTIES OF PALLADIUM NANOCLUSTERS SYNTHESIZED WITHIN DIBLOCK COPOLYMER FILMS - HYDROGENATION OF ETHYLENE AND PROPYLENE

Palladium nanoclusters were synthesized within microphase-separated di block copolymer films of [MTD](113)[Pd(Cp-N)PA](50) (MTD = methyltetra cyclododecene, Cp-N = endo-2-(cyclopentadienylmethyl) norborn-5-ene, P A = eta(3)-1-phenylallyl). The organometallic repeat units were reduce d by exposing the films to hydrogen at 100 degrees C, leading to the f ormation of nearly monodisperse palladium nanoclusters. TEM, SAXS, and WAXS were used to characterized the polymer morphology and cluster si ze. The nanocomposites were active catalysts for hydrogenation of ethy lene and propylene. The cluster size and voids within the polymer matr ix were important factors in determining the catalyst activity, expres sed as the moles of alkene hydrogenated per mole palladium per second. In contrast to permeation results that showed that the permeability o f propylene in polyMTD is greater than that of ethylene, the catalyst activity for hydrogenation of ethylene was greater than that for propy lene. (C) 1998 Elsevier Science Limited.