Functional initiators for the ring-opening polymerization of polyesters and polycarbonates: An overview

Functional ring-opening polymerization (ROP) initiators can instill a wide array of chemical, physical, and biological effects into a polymeric chain. Highlighting the versatility of this "active" initiator approach, a broad range of characteristics can be achieved through the use of initiators with chemistries spanning from drugs and dyes (key in the case of drug delivery or nanoparticle applications) through to radically active monomers, polymerization transfer agents, and catalysts. The selection of a suitable "active" initiator (monomers for tandem reactions, dyes, drugs, stereo-catalysts, etc.) can not only provide the final polymers with interesting application potential but also facilitate the implementation of ROP reactions in tandem with other polymerization techniques. Overall, this review will highlight that functionalities and properties can be effectively tuned by exploiting simple chemistry approaches, allowing readers to identify how these approaches could be of benefit to their own work in a range of applications including drug/gene delivery, amphiphilic bio/degradable carriers, drug/scent controlled release, and stereo-controlled polymers.