A new strategy for sustainable polymer recycling using an enzyme: poly(ɛ-caprolactone)

Enzymatic degradation and polymerization using an enzyme were analyzed with respect to the establishment of a sustainable chemical recycling system for poly(ε-caprolactone) (PCL) which is a typical biodegradable synthetic plastic. As the typical example, the enzymatic degradation of PCL having an Mn of 110 000 using lipase CA in toluene containing water at 70°C for 6 h afforded a unimodal oligomer having an Mn of about 1 000 quantitatively consisting of linear and cyclic oligomers. This was again polymerized by lipase CA in toluene under restricted water concentration to produce PCL having an Mn of greater than 70 000.