Feature Article: Heterotactic Polymers of Methacrylates and Their Properties

Heterotactic (ht-) polymer is a kind of stereoregular polymer, which consists of an alternate arrangement of meso (m) and racemo (r) diads. Heterotactic polymerization requires a higher order of stereocontrol than isotactic and syndiotactic polymerizations, because opposite stereoselectivities, m-addition and r-addition, have to occur in an alternate manner for the formation of ht-sequence, …mrmrmr…. We have succeeded in preparing highly heterotactic polymers with mr contents over 90% by a living polymerization of methacrylates with t-C4H9Li and bis(2,6-di-t-butylphenoxy)methylaluminum. Mechanism of the stereoregulation was discussed with the aid of NMR and supercritical fluid chromatographic analyses of the stereoregularity both at in-chain and chain-ends. Some properties of ht-polymethacrylates are also described.