Polymerization of racemic beta-butyrolactone using supported catalysts: a simple access to isotactic polymers.

Grafting of [Ln(BH(4))(3)(THF)(3)] (Ln = La, Nd) onto silica affords materials containing well-identified bis(borohydride) surface species. The neodymium-decorated silica converts the beta-butyrolactone monomer into highly isotactic poly(beta-hydroxybutyrate). Under similar conditions, the molecular precursor gives rise to an atactic polymer.