Structure−function relationships for multivalent polymer scaffolds are highly complex due to the wide diversity of architectures offered by such macromolecules. Evaluation of this landscape has traditionally been accomplished case-by-case due to the experimental difficulty associated with making these complex conjugates. Here, we introduce a simple dualwavelength, two-step polymerize and click approach for making combinatorial conjugate libraries. It proceeds by incorporation of a polymerization friendly cyclopropenone-masked dibenzocyclooctyne into the side chain of linear polymers or the α-chain end of star polymers. Polymerizations are performed under visible light using an oxygen tolerant porphyrin-catalyzed photoinduced electron/energy transfer-reversible addition− fragmentation chain-transfer (PET-RAFT) process, after which the deprotection and click reaction is triggered by UV light. Using this approach, we are able to precisely control the valency and position of ligands on a polymer scaffold in a manner conducive to high throughput synthesis.

A pH responsive pMAA nanogel that demonstrates high loading capacity and rapid intracellular delivery of hydrophilic peptides.

We show that photoinitiated electron/energy transfer–reversible addition–fragmentation chain transfer (PET-RAFT) enables vastly superior control over the polymerization of multiblock star copolymers compared to conventional techniques. Monomodal distributions with dispersities <1.3 could be achieved after the 10th block despite pushing the polymerization to >95% conversion in each block extension. The improvement in control is likely due to the reabsorption of the free radical at the propagating chain end by the excited catalyst, which would otherwise lead to a termination product. Simple modeling shows the dramatic effect that this has in the case of star polymerizations. Because PET-RAFT is also tolerant to oxygen, we were able to automate the synthesis of up to heptablock stars at short block lengths, providing a useful technique for screening the effect of polymer composition on the solution structure.