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1. RAFT step-growth polymerization via the Z-group approach and deconstruction by RAFT interchange

   https://doi.org/10.1039/d3sc06736j  

   Li, Jiajia; Tanaka, Joji; Li, Qing; Jing_Wang, Claire Jing; Sheiko, Sergei; Clouthier, Samantha Marie; Zhu, Jian; You, Wei (March 2024, Chemical Science)

   RAFT step-growth polymerizationviathe Z-group approach was developed, offering a facile method to prepare deconstructable (multiblock) polymers by combining RAFT chain-growth polymerization and RAFT interchange. 

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2. Photo‐Mediated RAFT Step‐Growth Polymerization With Diacrylate Monomers: Investigating Versatility and Oxygen Tolerance

   https://doi.org/10.1002/marc.202400602  

   Clouthier, Samantha Marie; Li, Jiajia; Tanaka, Joji; You, Wei (January 2025, Macromolecular Rapid Communications)

   Abstract Photomediated reversible addition fragmentation chain transfer (RAFT) step‐growth polymerization is performed using a trithiocarbonate‐based chain transfer agent (CTA) and acrylate‐based monomers both with and without a photocatalyst. The versatility of photo‐mediated RAFT step‐growth is demonstrated by one‐pot synthesis of a graft copolymer via sequential monomer addition. Furthermore, oxygen‐tolerant photo‐mediated RAFT step‐growth is demonstrated, facilitated by the appropriate selection of photocatalyst and solvent pair (zinc tetraphenyl porphyrin [ZnTPP] and dimethyl sulfoxide [DMSO]), enabling ultralow volume polymerization under open‐air conditions. 

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3. Mechanism and modelling of photo-mediated RAFT step-growth polymerization

   https://doi.org/10.1039/d5py00185d  

   Clouthier, Samantha Marie; Li, Jiajia; Tanaka, Joji; You, Wei (January 2025, Polymer Chemistry)

   Here, we report the modelling of photo-mediated RAFT step-growth polymerization kinetics of maleimide and acrylate monomers with bifunctional RAFT agents bearing tertiary carboxyalkyl stabilized fragementable R groups. 

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4. Mechanism and modelling of thermally initiated RAFT step-growth polymerization

   https://doi.org/10.1039/d4py01188k  

   Clouthier, Samantha Marie; Tanaka, Joji; You, Wei (January 2025, Polymer Chemistry)

   Here we report the modelling of thermally initiated RAFT step-growth polymerization kinetics of maleimide and acrylate monomers with bifunctional RAFT agents bearing tertiary carboxyalkyl-stabilized fragmentable R groups. 

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5. Radical–radical coupling effects in the direct-growth grafting-through synthesis of bottlebrush polymers using RAFT and ROMP

   https://doi.org/10.1039/d2py00794k  

   Alaboalirat, Mohammed; Vu, Clark; Matson, John B. (October 2022, Polymer Chemistry)

   The direct-growth technique was used to synthesize several macromonomers (MMs) employing reversible addition–fragmentation chain transfer (RAFT) polymerization by growing directly from a norbornene-functionalized chain transfer agent (CTA). We aimed to investigate the formation of bisnorbornenyl species resulting from radical termination by combination ( i.e. , coupling) during RAFT polymerization at different monomer conversion values in four types of monomers: styrene, tert -butyl acrylate, methyl methacrylate and N -acryloyl morpholine. Ring-opening metathesis polymerization (ROMP) of these MMs using Grubbs' 3rd generation catalyst (G3) at an MM : G3 ratio of 100 : 1 resulted in the formation of bottlebrush polymers. Analysis by size-exclusion chromatography (SEC) revealed high molar mass shoulders of varying intensities attributed to the incorporation of these bisnorbornenyl species to generate dimeric or higher-order bottlebrush polymer oligomers. The monomer type in the RAFT step heavily influenced the amount of these bottlebrush polymer dimers and oligomers, as did the monomer conversion value in the RAFT step: We found that the ROMP of polystyrene MMs with a target backbone degree of polymerization of 100 produced detectable coupling at ≥20% monomer conversion in the RAFT step, while it took ≥80% monomer conversion to observe coupling in the poly( tert -butyl acrylate) MMs. We did not detect coupling in the poly(methyl methacrylate) MMs, but broadening of the SEC peaks and an increase in dispersity occurred, suggesting the presence of metathesis-active alkene-containing chain ends created by disproportionation. Finally, poly( N -acryloyl morpholine) MMs, even when reaching 90% monomer conversion in the RAFT step, showed no detectable coupling in the bottlebrush polymers. These results highlight the importance of monomer choice and RAFT polymerization conditions in making MMs for ROMP grafting-through to make well-defined bottlebrush polymers. 

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