Coronae of block copolymer micelles as supports for organometallic catalysis

This thesis presents the results of several studies, the overall goal of which was the design and understanding of a block copolymer micelle in which the coronal chains act as a catalyst support for organometallic species. A model system consisting of reverse micelles of polystyrene-block -poly (sodium acrylate), PS-b-PANa, with coronal chain composed of ca. 210 styrene repeat units and a core radius of ca. 3.0 nm was used in the first study. The coronal chains were loaded to varying extents with Cr(CO)3 fragments in an effort to observe the effect of loading on the corona. The hydrodynamic radii, Rh, were measured by dynamic light scattering, DLS, and compared to a similarly treated sample of PS homopolymer. An increase in Rh by a factor of 3.4 was observed in the micelles, compared to only 1.5 in the homopolymer. A new block copolymer aggregate consisting of Poly (4-bromostyrene)-block-poly(4-vinylphenol), PBS- b-P4VPOH, in which the P4VPOH block could be used to crosslink the core, was developed for use as a coronal support for catalytically active organometallic species. bis-dimethylaminodimethylsilane was used to generate a crosslinked network of siloxane linkages within the core, resulting in a stable micelle. KPPh2 was then reacted with the PBS corona of the micelle to convert the bromostyrene units to analogues of triphenylphosphine. These micelles were then successfully loaded with a rhodium based catalyst. Catalytic activity was tested using the hydrogenation of 1-decene as a model reaction, in which turn-over frequencies of ca. 130 were achieved. The expansion seen in the first study also prompted an effort to develop a theoretical model of coronal chain behavior. A combined hypernetted-chain, mean spherical, Monte-Carlo method was used to model the corona of a micelle. The potential governing the interactions between repeat units was modified to include the effect of having several different species present along the chains. T