Andrew Lowe and Charles Hoyle from the University of Southern Mississippi, USA, have developed a facile, one-pot convergent preparation of three arm star polymers. They utilised a two-step process involving initial thiocarbonylthio end-group reduction (on a RAFT-prepared precursor polymer) followed by phosphine catalyzed thiol-ene addition to a triacrylate. This is the first time that the thiol-ene click reaction has been used to prepare star polymers. 

                    

Star polymers are the simplest examples of branched polymers, with all arms extending from a single branching point. Currently, the 'gold standard' in click-chemistry is the Cu(I) mediated reaction between an alkyne and an azide, which is an exceptionally efficient and selective reaction. However, the thiol-ene reaction used here has advantages including the use of benign starting materials and catalysts. Additionally, the thiol-ene reaction is extremely rapid. 

'Given the current interest in click chemistry, we anticipate that the thiol-ene reaction will be widely adopted and used as a synthetic tool in polymer/materials chemistry for the synthesis of complex molecules and for site-specific functionalization, and in small molecule organic chemistry/drug discovery as a convenient, facile approach for introducing functionality in a controlled manner' says Lowe. 

Kathryn Sear