Stereochemistry of the free-radical polymerization of zinc methacrylates coordinated with a bidentate ligand

The polymerization of zinc methacrylates coordinated with a bidentate ligand (1-4) was carried out in chloroform at 60 degreesC. The polymerization of these monomers gave chloroform-insoluble polymers. Stereoregularity of the polymers was estimated from H-1 NMR spectra of poly(methyl methacrylate)s (PMMAs) derived from the original polymers. Monomers 1 and 2 gave slightly different polymers compared with conventional ones obtained by polymerization of methacrylic acid, while 3 afforded higher amounts of isotactic polymers than 1 and 2. Conversely, 4 gave a polymer of high syndiotacticity. Furthermore, the relationship between triad tacticity and monomer concentration in the feed was studied. Consequently, it was demonstrated that the structure of bidentate ligands coordinated with zinc ion influences the stereoregularity of the resulting polymers.