A Cation-Dependent Dual Activation Motif for Anionic Ring-Opening Polymerization of Cyclic Esters.

A new organocatalyst for the ring-opening polymerization of lactones has been identified. Under the tested conditions, the anions of 2,2'-bisindole promote fast, living polymerizations (as short as 10 ms) which are selective for chain elongation over transesterification (Đ ≤ 1.1).

Block copolymer composition drives function of self-assembled nanoparticles for delivery of small-molecule cargo.

Nanoparticles are useful for the delivery of small molecule therapeutics, increasing their solubility, residence time, and stability. Here, we used organocatalytic ring opening polymerization to produce amphiphilic block copolymers for the formation of nanoparticle drug carriers with enhanced stability, cargo encapsulation, and sustained delivery. These polymers comprised blocks of poly(ethylene glycol) (PEG), poly(valerolactone) (PVL), and poly(lactide) (PLA).

Programmable High-Throughput Platform for the Rapid and Scalable Synthesis of Polyester and Polycarbonate Libraries.

The critical role of composition, architecture, molecular weight, and molecular weight distribution on the functional properties of macromolecular materials underscores the need for reproducible, robust, scalable, and programmable synthetic methods to generate macromolecules that span a systematic and wide range of structure-property space. Herein, we describe the marriage of tunable and highly active organic catalysts with programmed continuous-flow reactors to rapidly generate libraries of polyester and polycarbonate homopolymers and block copolymers with exquisite efficiency and control. Under continuous-flow conditions, highly controlled polymerizations occur with residence times as low as 6 ms (TOF = 24 000 000 h) and can be readily scaled-up to generate polymers at a rate of tens of grams per minute.

Urea Anions: Simple, Fast, and Selective Catalysts for Ring-Opening Polymerizations.

Aliphatic polyesters and polycarbonates are a class of biorenewable, biocompatible, and biodegradable materials. One of the most powerful methods for accessing these materials is the ring-opening polymerization (ROP) of cyclic monomers. Here we report that the deprotonation of ureas generates a class of versatile catalysts that are simultaneously fast and selective for the living ring-opening polymerization of several common monomers, including lactide, δ-valerolactone, ε-caprolactone, a cyclic carbonate, and a cyclic phosphoester.