RAFT-Based Polymers for Click Reactions

The parallel development of reversible deactivation radical polymerization and click reaction concepts significantly enriches the toolbox of synthetic polymer chemistry. The synergistic effect of combining these approaches manifests itself in a growth of interest to the design of well-defined functional polymers and their controlled conjugation with biomolecules, drugs, and inorganic surfaces. In this review, we discuss the results obtained with reversible addition-fragmentation chain transfer (RAFT) polymerization and different types of click reactions on low- and high-molar-mass reactants. Our classification of literature sources is based on the typical structure of macromolecules produced by the RAFT technique. The review addresses click reactions, immediate or preceded by a modification of another type, on the leaving and stabilizing groups inherited by a growing macromolecule from the chain transfer agent, as well as on the side groups coming from monomers entering the polymerization process. Architecture and self-assembling properties of the resulting polymers are briefly discussed with regard to their potential functional applications, which include drug delivery, protein recognition, anti-fouling and anti-corrosion coatings, the compatibilization of polymer blends, the modification of fillers to increase their dispersibility in polymer matrices, etc.

Control over the relative reactivities of monomers in RAFT copolymerization of styrene and acrylic acid

The relative monomer reactivities in the reversible addition–fragmentation chain transfer (RAFT) radical copolymerization of styrene (S) and acrylic acid (AA) in a solution of the polar solvent N,N-dimethylformamide are found to be dependent on the chemical nature of the RAFT agent. Polymeric RAFT agents based on polyacrylic acid enhance the difference in monomer reactivities (dithiobenzoate – r_AA = 0.09 ± 0.02, r_S = 3.5 ± 1.2, trithiocarbonate – r_AA = 0.08 ± 0.04, r_S = 3.03 ± 1.78) compared to low molecular weight RAFT agents (dibenzyl dithiobenzoate – r_AA = 0.14 ± 0.01, r_S = 1.00 ± 0.01, dibenzyl trithiocarbonate – r_AA = 0.08 ± 0.01, r_S = 0.85 ± 0.03). The opposite effect on the relative reactivity of acrylic acid is observed when polymeric RAFT agents based on polystyrene are used (dithiobenzoate – r_AA = 3.3 ± 0.4, r_S = 0.72 ± 0.05, trithiocarbonate – r_AA = 0.11 ± 0.01, r_S = 0.54 ± 0.03). In all the investigated systems the copolymers formed are characterized by narrow MWD due to the high efficiency of the chosen RAFT agents.

The tuning of the relative monomer reactivities of styrene and acrylic acid in a solution of N,N-dimethylformamide by using polymeric RAFT agents.

A translation of the structure of mussel byssal threads into synthetic materials by the utilization of histidine-rich block copolymers

The self-healing capacities of mussel-inspired metallopolymers based on block copolymers containing histidine are briefly presented.

Synthesis of amphiphilic copolymers based on acrylic acid, fluoroalkyl acrylates and n-butyl acrylate in organic, aqueous–organic, and aqueous media via RAFT polymerization

Hydrophilic and amphiphilic polymeric trithiocarbonates based on polyacrylic acid are able to provide polymerization-induced self-assembly in copolymerization of butyl and fluoroalkyl acrylates.

RAFT polymerization to form stimuli-responsive polymers

Stimuli-responsive polymers respond to a variety of external stimuli, which include optical, electrical, thermal, mechanical, redox, pH, chemical, environmental and biological signals. This paper is concerned with the process of forming such polymers by RAFT polymerization.