Scientists in France have synthesized a biodegradable polymer derived from glutamic acid.

Blanca Martin-Vaca, Didier Bourissou and colleagues from Université Paul Sabatier, Toulouse have prepared polyesters functionalized with pendant carboxylic acid groups from renewable resources (lactic and glutamic acids). These can be formed in a controlled fashion and under mild conditions.

Biodegradable polymers are finding applications in many different fields from medical to commodity applications. One of the most important families of biodegradable polymers is that derived from a-hydroxyacids and in particular polylactic acid (PLA). A drawback in the use of these polymers is the limitation in the modulation of the polymer backbone in order to target new applications. 

The various routes developed so far to prepare functionalized poly (alpha-hydroxyacids) often require harsh polymerisation conditions to finally yield polymers of low molecular weight and poorly controlled properties. Bourissou and co-workers have already demonstrated that the O-carboxyanhydride deriving from lactic acid is a readily available, activated equivalent of lactide. They decided to extrapolate this strategy to functionalize monomers, and became interested in the organo-catalyzed ring-opening polymerization of O-carboxyanhydrides derived from natural amino acids, such as glutamic acid.

The next stage for this work will be to take advantage of the pool of natural amino-acids available. 'The nature of the pendant functional groups introduced on the polymer backbone could be easily varied affording a broad range of functionalized polyesters. Also, by varying the number and variety of pendant functional groups, the physico-chemical properties of the polymers could be modulated finely, and the application fields of these biomaterials can be further extended,' said Bourissou.

A future challenge that this research area faces is that 'this approach already competes with coordination-insertion polymerizations mediated by metal salts in terms of activity and control, and would therefore be further improved if high stereocontrol could also be achieved,' said Bourissou. 

Emma Shiells