Cationic Single-Unit Monomer Insertion (cSUMI): From Discrete Oligomers to the α-/ω-End and In-Chain Sequence-Regulated Polymers

Abstract

Single-unit monomer insertion (SUMI) has become an important strategy for the synthesis of sequence-controlled vinyl polymers due to its strong versatility and high efficiency. However, all reported SUMI processes are based on a free-radical mechanism, resulting in a limited number of monomer types being applicable to SUMI or a limited number of sequences of structural units that SUMI can synthesize. Herein, we developed a novel SUMI based on a cationic mechanism (cSUMI), which operates through a degenerative (similar to radical SUMI) but cationic chain transfer process. By optimizing the chain transfer agent (CTA) and monomer pairs, a high-efficiency cSUMI was achieved for vinyl ether and styrene monomers. Based on this reaction, a range of discrete oligomers containing vinyl ether and styrene moieties, and even α-/ω-end and in-chain sequence-regulated polymers were synthesized, most of which cannot be achieved by radical SUMI. In addition, we explored the application of these sequence-regulated polymers in the preparation of miktoarm star polymers, delivery of photosensitizers, and solubilization of fluorescence probes. The development of SUMI with a new mechanism will certainly broaden the scope of structures and sequences in precise vinyl-based polymers.

Simple Monomers for Precise Polymer Functionalization During Ring-Opening Metathesis Polymerization

“…Such monomers typically act to deactivate the propagating center, e.g., through electronic modification, steric hindrance, or chelation, precluding further additions until the propagating center is reactivated. While single-addition monomers have been reported for anionic, , cationic, − radical, − ring-opening, and ring-opening metathesis polymerizations (ROMPs), ,,,, most possess very low reactivity such that long reaction times (h to d) and stoichiometric excess are required to achieve quantitative active site conversion. Thus, the majority of reported single-addition monomers are unsuitable for the types of midchain, stoichiometric reactions during the SAMs envisioned earlier.…”

Solid-phase synthesis of iterative RAFT single unit monomer insertion adducts

“…Despite these achievements, there has been almost no developments in using solid-phase synthesis towards creating sequence-defined macromolecules with all-carbon backbones, such as those found in vinyl-derived polymers, with most advances centred around single-step sequence-controlled copolymerisations. [11][12][13][14] Yet, vinyl-derived macromolecules are arguably among the most commonly studied and manufactured class of synthetic macromolecules.…”

Accelerated Activity-Based Sensing by Fluorogenic Reporter Engineering Enables to Rapidly Determine Unstable Analyte

“…Generally, surfactant effect is available to elevate reaction kinetic of the probe to achieve fast response . Inspired by this, nanomaterial-assisted approach by polymer, graphene oxide (GO), , and metal–organic frameworks (MOFs) has been developed to accelerate activity based sensing to date. However, a faint noncovalent interaction between them would restrict reliability under complicated physiological environments.…”