Clickable Polylactic Acids by Fast Organocatalytic Ring-Opening Polymerization in Continuous Flow

The use of microreactor technology for the ring-opening polymerization of L-lactide catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene allows for rapid optimization of reaction parameters (reaction temperature and residence time). At moderate catalyst loading, good control over the polymerization is demonstrated by high conversion of monomer (>95%) and low polydispersity (<1.3) at residence times as low as 2 s. This metal-free, organocatalytic route yields well-defined poly(lactic acid) in continuous flow and by using bicyclononyne- and tetrazine-containing initiators gives access to poly(lactic acid) amenable to click chemistry.