Yellow, navy, maroon, midnight blue – what color shall it be? Milan-based researchers have found a way to synthesize different kinds of polyesters, their color being dependent on the starting substance only. “We are confident that these materials might find useful applications in the dye and paint industries,” Cristina Navarra and her co-authors write.

The researchers at Institute of Molecular Recognition in Milan, Italy and at the University of Milan used an enzyme-catalyzed ring-opening polymerization: they heated a colored amine or alcohol with an excess of the colorless liquid ε-caprolactone overnight. With the help of the enzyme Novozym 435, the ε-caprolactone ring was opened and several molecules were linked together, with the initial amine or alcohol at the beginning of the chain.

The researchers could modulate the polymer length by changing the amine:caprolactone ratio. The chain length varied between 10 and 39 monomers. Almost all synthesized polyesters were colored powdery solids, the researchers write; one product, however, was a viscous oil.

Image: (c) Wiley-VCH

• Chemoenzymatic Synthesis of Fluorescent and Colored Polyesters
  C. Navarra, M. Marzorati, B. Danieli, S. Riva,
  ChemCatChem 2010.
  DOI: 10.1002/cctc.201000327