Metallocene-catalyzed polymerization of functionalized alkenes within silicate nanogalleries and in solution

Abstract

The research presented herein studies the polymerization of functionalized alkenes such as (meth)acrylates and acrylamides catalyzed by early transition metallocenium complexes within layered silicate nanogalleries and in solution. Key findings of this study include: (a) the first in situ production of exfoliated silicate nanocomposites consisting of stereochemically controlled poly(methyl methacrylate) [P(MMA)] matrices using intergallery anchored metallocenium cations, (b) development of the novel, highly isospecific and living polymerization of acrylamides catalyzed by metallocenium enolate complexes, (c) identification of the chain transfer and termination processes occurring in the polymerization of acrylates by metallocene complexes that prevent the formation of high molecular weight polymer, and (d) the isolation and structural characterization of three new cationic and zwitterionic tantalocene complexes that are relevant to the polymerization of MMA and N,N-dimethylacrylamide (DMAA) by group(V) tantalocenes. The broad focus of this dissertation concerns the mechanisms of the polymerization of polar vinyl monomers by highly reactive, electrodeficient, cationic metallocene complexes. In return, this dissertation work has also provided several advanced and potentially useful polymeric materials: exfoliated silicate/stereoregular P(MMA) nanocomposites, stereo-defect free and high melting transition temperture isotactic P(DMAA), as well as the amphiphilic stereodiblock copolymer P(MMA)-b-P(DMAA).