Site‐Selective, Multistep Functionalizations of CO₂‐Based Hyperbranched Poly(alkynoate)s toward Functional Polymetric Materials

Hyperbranched polymers constructed from CO₂ possess unique architectures and properties; however, they are difficult to prepare. In this work, CO₂-based, hyperbranched poly(alkynoate)s (hb-PAs) with high molecular weights and degrees of branching are facilely prepared under atmospheric pressure in only 3 h. Because hb-PAs possess two types of ethynyl groups with different reactivities, they can undergo site-selective, three-step functionalizations with nearly 100% conversion in each step. Taking advantage of this unique feature, functional hb-PAs with versatile properties are constructed that could be selectively tailored to contain hydrophilic oligo(ethylene glycol) chains in their branched chains, on their periphery, or both via tandem polymerizations. Hyperbranched polyprodrug amphiphiles with high drug loading content (44.3 wt%) are also generated, along with an artificial light-harvesting system with high energy transfer efficiency (up to 92%) and white-light-emitting polymers. This work not only provides an efficient pathway to convert CO₂ into hyperbranched polymers, but also offers an effective platform for site-selective multistep functionalizations toward functional polymeric materials.