(A syndiotactic polymer
is a stereo-regular polymer made by a metallocene catalyst, which assembles "handed" monomers with pendant groups, or "thumbs," on alternating sides of the polymer chain, giving distinctive strength and clarity.
Polypropylenes (PP) synthesized using traditional Ziegler-Natta catalysts are generally about 95% isotactic, with a few percent atactic and some syndiotactic polymer
. Metallocene-based isotactic poly-propylene, with much finer control of tacticity, has been developed by Chisso, Exxon, and Hoechst.
Triphenylmethyl methacrylate (TrMA) is a unique monomer that forms an isotactic polymer, PTrMA, even by a radical process, (11) which usually yields atactic or syndiotactic polymers
. This unusual feature of TrMA had been considered to be due to the helical conformation of the polymer chain induced by the steric repulsion of the bulky triphenylmethyl groups, although nothing was known about the stability of the helix.