Photo-Deactivation Strategy for Switchable ATRP with the Assistance of Molecular Switches.

Light irradiation is an external stimulus, rapidly developed in switchable atom transfer radical polymerization (ATRP) via photo-activation methods in recent years. Herein, a photo-deactivation strategy is introduced to regulate ATRP with the assistance of photoswitchable hexaarylbiimidozole (HABI). Under visible light irradiation and in the presence of HABI, ATRP is greatly decelerated or quenched depending on the concentration of HABI.

Tailoring Polymerization Controllability and Dispersity Through a Photoswitchable Catalyst Strategy.

Modulating on-demand polymerization is a challenge in synthetic macromolecules. Herein, tailoring polymerization controllability and dispersity during single-electron transfer mediated living radical polymerization (SET-LRP) of methyl methacrylate (MMA) is achieved. Hexaarylbiimidazole (HABI) is employed as a photoswitchable catalyst, allowing reversible control of catalytic activity between an active and inactive state.

Regenerable-Catalyst-Aided, Opened to Air and Sunlight-Driven "CuAAC&ATRP" Concurrent Reaction for Sequence-Controlled Copolymer.

An ideal stimuli-responsive controlled/living radical polymerization should have the ability to manipulate the reaction through spatiotemporal "on/off" controls, achieving the polymerization under fully open conditions and allowing for precise control over macromolecular architecture with defined molecular weights and monomer sequence. In this contribution, the photo (sunlight)-induced electron transfer atom transfer radical-polymerization (PET-ATRP) can be realized to be reversibly activated and deactivated under fully open conditions utilizing one-component copper(II) thioxanthone carboxylate as multifunctional photocatalyst and oxygen scavenger. The polymerization behaviors are investigated, presenting controlled features with first-order kinetics and linear relationships between molecular weights and monomer conversions.

Natural RAFT Polymerization: Recyclable-Catalyst-Aided, Opened-to-Air, and Sunlight-Photolyzed RAFT Polymerizations.

The successful sunlight-photolyzed reversible addition-fragmentation chain transfer (RAFT) photopolymerization can be reversibly activated and deactivated by irradiation with sunlight in the absence of photocatalyst and photoinitiator. In the present work, the thiocarbonylthio compounds (dithiobenzoate, trithiocarbonate, and xanthate) can all be employed to carry out the polymerization under sunlight irradiation acting as an initiator, chain transfer agent, and termination agent. Moreover, it was demonstrated that the recyclable-catalyst-aided, opened-to-air, and sunlight-photolyzed RAFT (ROS-RAFT) polymerizations can be successfully carried out to fabricate precise and predictable polymers in the presence of the recyclable magnetic semiconductor nanoparticles (NPs).

Initiator and Photocatalyst-Free Visible Light Induced One-Pot Reaction: Concurrent RAFT Polymerization and CuAAC Click Reaction.

A new, visible light-catalyzed, one-pot and one-step reaction is successfully employed to design well-controlled side-chain functionalized polymers, by the combination of ambient temperature revisible addtion-fragmentation chain transfer (RAFT) polymerization and click chemistry. Polymerizations are well controlled in a living way under the irradiation of visible light-emitting diode (LED) light without photocatalyst and initiator, using the trithiocarbonate agent as iniferter (initiator-transfer agent-terminator) agent at ambient temperature. Fourier transfer infrared spectroscopy (FT-IR), NMR, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) data confirm the successful one-pot reaction.