Click reactions have provided access to an array of remarkably complex polymer architectures. However, the term “click” is often applied inaccurately to polymer ligation reactions that fail to respect the criteria that typify a true “click” reaction. With the purpose of providing a universal way to benchmark polymer–polymer coupling efficiency at equimolarity and thus evaluate the fulfilment of click criteria, we report a simple one-pot methodology involving the homodicoupling of α-end-functionalized polymers using a small-molecule bifunctional linker. A combination of SEC analysis and chromatogram deconvolution enables straightforward quantification of the coupling efficiency. We subsequently employ this methodology to evaluate an overlooked candidate for the click reaction family: the addition of primary amines to α-tertiary isocyanates (α-tNCO). Using our bifunctional linker coupling strategy, we show that the amine–tNCO reaction fulfills the criteria for a polymer–polymer click reaction, achieving rapid, chemoselective, and quantitative coupling at room temperature without generating any byproducts. We demonstrate that amine–tNCO coupling is faster and more efficient than the more common amine–tertiary active ester coupling under equivalent conditions. Additionally, we show that the α-tNCO end group is unprecedentedly stable in aqueous media. Thus, we propose that the amine–tNCO ligation is a powerful new click reaction for efficient macromolecular coupling.

The synthesis of multiblock copolymers is often considered to be synthetically challenging and time consuming. In this contribution, the development of a remarkably efficient and versatile procedure to access multiblock copolymers via reversible addition–fragmentation chain transfer (RAFT) polymerization is reported. The robustness and versatility of the RAFT process are demonstrated in this report by preparing multiblock copolymers using uncommon experimental conditions. The synthesis of each block was performed in the presence of air and only required 3 minutes to reach near full monomer conversion. This approach removes the necessity to deoxygenate the solution and allows access to complex copolymer structures in very short time periods. For example, this process allowed the preparation of a heptablock homopolymer with a well-defined architecture in just 21 minutes. We also discuss the limitations inherent to this approach. This strategy is shown to be particularly efficient when blocks with low degrees of polymerization (DP < 20) are targeted. For blocks with higher DPs (DP > 50), the procedure is typically limited to the preparation of di- or triblock copolymers.