High activity of rare earth tetrahydroborates for ring‐opening polymerization of ω‐pentadecalactone

Ring‐opening polymerization of ω‐pentadecalactone (PDL) by tetrahydroborate complexes of rare earth metals, Ln(BH 4 ) 3 (THF) 3 (Ln = La ( 1 ), Nd ( 2 ), Y ( 3 )), was studied. These complexes showed high activity for PDL polymerization in THF at 60°C. Among the complexes 1 – 3 , the neodymium complex 2 was most active. The obtained poly(PDL) was demonstrated to be hydroxy‐telechelic by 1 H‐NMR and MALDI‐TOF MS spectroscopy. Biodegradation of the poly(PDL) in compost at 60°C was investigated, where 18% weight loss of the samples was observed after 280 days.