Scientists in France have discovered a new low temperature route to biodegradable and biocompatible polymers.

Jean-Francois Carpentier and colleagues at the University of Rennes have used a transition metal catalyst to promote the ring-opening polymerisation of 2,5-morpholinedione at temperatures of 60-100°C. 

The polydepsipeptides synthesised are copolymers with alternating units of alpha-amino and alpha-hydroxy acids. These polymers are very attractive 'green' materials because they are made from renewable resources as well as being highly biodegradable and biocompatible.

Previously, polymerisation of morpholinediones was found to proceed only with tin-based initiators under severe conditions, explained Carpentier. However, in this method a yttrium complex acts as a catalyst for the polymerisation at much lower temperatures. 

Carpentier used mass spectrometry and NMR spectroscopy to determine the mechanism of the polymerisation, which was found to be a coordination-insertion route. According to Carpentier, 'this knowledge is of fundamental importance for further rational design of more effective catalysts and monomers.' 

In the future, the researchers hope to modify the synthesis to make polydepsipeptides even more efficiently and with a higher degree of control.  

Alison Stoddart