Reversible addition–fragmentation chain-transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP) are the two most common controlled radical polymerization methods. Both methods afford functional polymers with a predefined length, composition, dispersity and end group. Further, RAFT and ATRP tame radicals by reversibly converting active polymeric radicals into dormant chains. However, the mechanisms by which the ATRP and RAFT methods control chain growth are distinct, so each method presents unique opportunities and challenges, depending on the desired application. This Perspective compares RAFT and ATRP by identifying their mechanistic strengths and weaknesses, and their latest synthetic applications. Reversible addition–fragmentation chain-transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP) are evaluated in terms of their mechanistic strengths and weaknesses, versatility and latest synthetic advances.

A comparison of RAFT and ATRP methods for controlled radical polymerization

High molecular weight star-shaped polystyrenes were prepared via the coupling of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) terminated polystyrene oligomers with divinylbenzene (DVB) in m-xylene at 138 °C. The optimum ratio of the coupling solvent (m-xylene) to divinylbenzene was determined to be 9 to 1 based on volume. Linear polystyrene oligomers (M n = 19,300 g/mol, M w /M n = 1.10) were prepared in bulk styrene using benzoyl peroxide in the presence of TEMPO at approximately 130 °C under an inert atmosphere. Coupling of the TEMPO-terminated oligomers under optimum conditions resulted in a product with a number average molecular weight exceeding 300,000 g/mol (M w /M n = 3.03) after 24 h, suggesting the formation of relatively well-defined star-shaped polymers. Additionally, the intrinsic viscosities of the star-shaped products were lower than calculated values for linear analogs of equivalent molecular weight, which further supported the formation of a star-shaped architecture.

Synthesis of star-shaped polystyrenes via nitroxide-mediated stable free radical polymerization

https://hal.archives-ouvertes.fr/hal-02493982/document

Synthesis and functionalization of hyperbranched polymers for targeted drug delivery.

Facilely prepared blue-green light sensitive curcuminoids with excellent bleaching properties as high performance photosensitizers in cationic and free radical photopolymerization

Conjugated phenothiazine oxime esters as free radical photoinitiators

Controlled radical polymerization (CRP) or controlled/living radical polymerization has revolutionized the polymer industry as a tool for the preparation of a wide variety of polymers This process enables the preparation of polymers with good control of molecular weight, narrow polydispersity, and a range of architectures including block and graft copolymers, star polymers, and other functional polymers The mechanistic transformation reaction provides a great opportunity to tune chemical and physical properties of copolymers It can be applied to combine different homopolymers using post-modification techniques or by the use of a dual initiator, allowing the combination of mechanistically distinct polymerization reactions This review will cover CRP transformations including the synthesis of block copolymers with both linear structures (AB, ABA, (AB) n , multiblocks, etc) and branched macromolecular architectures (graft, miktoarm star, and dendritic-like), which are obtained by a combination of more than one form of living polymerization reaction

Xiaofeng Guo

Papers

Polymer Synthesis with More Than One Form of Living Polymerization Method.

D–D–A dyes with phenothiazine–carbazole/triphenylamine as double donors in photopolymerization under 455 nm and 532 nm laser beams

Synthesis of multifunctional miktoarm star polymers via an RGD peptide-based RAFT agent

A facile synthesis of pH stimuli biocompatible block copolymer poly(methacrylic acid)-block-poly(N-vinylpyrrolidone) utilizing switchable RAFT agents

Effect of solvents on the RAFT polymerization of N-(2-hydroxypropyl) methacrylamide