Convenient divergent synthesis of linear-dendron block polyphosphoesters via acyclic diene metathesis polymerization†
Abstract
A novel divergent approach was developed for the first time for the synthesis of linear-dendritic polyphosphoester (PPE) structures using an acrylated poly(ethylene glycol) methyl ether as a linear macromolecular chain stopper by acyclic diene metathesis (ADMET) polymerization of phosphoester functional asymmetric α,ω-diene monomers. This synthesis is remarkable, because unlike all others, each low-generation linear-dendron copolymer could be readily converted, by thiol-Michael addition click reaction and esterification, to a new selective macromolecular chain stopper by subsequent ADMET polymerization to synthesize high-generation linear-dendron block PPEs, and it requires no means of purification other than a simple precipitation. The prepared linear-dendritic PPEs can self-assemble spontaneously in a selective solvent to form polymeric nanoparticles, which were characterized in detail by DLS, AFM, and TEM analyses. To the best of our knowledge, this is the first report that describes the synthesis of linear-dendron-like block PPEs via ADMET polymerization. Consequently, this provides a versatile strategy not only for the synthesis of biodegradable and amphiphilic block PPEs with linear-dendron-like architecture but also for the fabrication of biocompatible nanoparticles with a suitable size for biomedical applications.