The invention provides novel polymer compositions and methods for preparing such compositions. The invention also provides methods for polymerizing various unsaturated monomers, including naturally occurring or plant biomass-derived renewable acrylic monomers. The monomers can be rapidly polymerized using various organic catalysts or organometallic catalysts, as described herein. In one embodiment, nearly perfectly isotactic polymers (mmmm>99%) can be prepared using a C2-symmetric zirconocenium catalyst.