Stereoregulating behaviour of organoalkali and organoalkaline earth compounds in polymerization of methyl methacrylate

Stereoregulating behaviour of organoalkali and organoalkaline earth metal compounds in methyl methacrylate (MMA) polymerization has been studied. Low temperature and polar solvents such as tetrahydrofuran (THF) favour formation of syndiotactic polymer when lithium and magnesium ketyls are used as catalysts. Whereas isotactic polymer is obtained with sodium ketyl even in THF at −70°C. Lithium aluminum hydride (LiAlH 4 ) gave almost complete isotactic polymer in high conversion in diethyl ether or toluene even at low temperature, and lithium aluminum tetraethyl (LiAlEt 4 ), on the other hand, gave very highly syndiotactic polymer under the same conditions. The solvent, besides, showed very important role in stereoregulation, that is, LiAlH 4 could give syndiotactic polymer in a polar solvent at low temperature. Polymer structure was analyzed by NMR‐ and IR‐spectroscopy. The electrical conductivities of these catalyst systems were measured and there was found a parallelism between those values and stereoregularities of polymers obtained by the respective catalyst systems.