Visible-Light-Mediated Controlled Radical Branching Polymerization in Water

Hyperbranched polymethacrylates were synthesized by green-light-induced atom transfer radical polymerization (ATRP) under biologically relevant conditions in the open air. Sodium 2-bromoacrylate (SBA) was prepared in situ from commercially available 2-bromoacrylic acid and used as a water-soluble inibramer to induce branching during the copolymerization of methacrylate monomers. As a result, well-defined branched polymethacrylates were obtained in less than 30 min with predetermined molecular weights (36 000<M_n <170 000), tunable degree of branching, and low dispersity values (1.14≤Đ≤1.33). Moreover, the use of SBA inibramer enabled the synthesis of bioconjugates with a well-controlled branched architecture.

Mechanoredox Catalysis Enables a Sustainable and Versatile Reversible Addition-Fragmentation Chain Transfer Polymerization Process

The sustainable synthesis of macromolecules with control over sequence and molar mass remains a challenge in polymer chemistry. By coupling mechanochemistry and electron-transfer processes (i.e., mechanoredox catalysis), an energy-conscious controlled radical polymerization methodology is realized. This work explores an efficient mechanoredox reversible addition-fragmentation chain transfer (RAFT) polymerization process using mechanical stimuli by implementing piezoelectric barium titanate and a diaryliodonium initiator with minimal solvent usage. This mechanoredox RAFT process demonstrates exquisite control over poly(meth)acrylate dispersity and chain length while also showcasing an alternative to the solution-state synthesis of semifluorinated polymers that typically utilize exotic solvents and/or reagents. This chemistry will find utility in the sustainable development of materials across the energy, biomedical, and engineering communities.

Main-Chain Fluoropolymers with Alternating Sequence Control via Light-Driven Reversible-Deactivation Copolymerization in Batch and Flow

Polymers with regulated alternating structures are attractive in practical applications, particularly for main-chain fluoropolymers. We for the first time enabled controlled fluoropolymer synthesis with alternating sequence regulation using a novel fluorinated xanthate agent via a light-driven process, which achieved on-demand copolymerization of chlorotrifluoroethylene and vinyl esters/amides under both batch and flow conditions at ambient pressure. This method creates a facile access to fluoropolymers with a broad fraction range of alternating units, low dispersities and high chain-end fidelity. Moreover, a two-step photo-flow platform was established to streamline the in-situ chain-extension toward unprecedented block copolymers continuously from fluoroethylene. Influences of structural control were illustrated with thermal and surface properties. We anticipate that this work will promote advanced material engineering with customized fluoropolymers.

Controlling mechanical properties of 3D printed polymer composites through photoinduced reversible addition–fragmentation chain transfer (RAFT) polymerization

Reversible addition–fragmentation chain-transfer (RAFT) polymerization has been exploited to design silica-nanoparticle-incorporated photocurable resins for 3D printing of materials with enhanced mechanical properties and complex structures.

Visible-Light-Enabled Organocatalyzed Controlled Alternating Terpolymerization of Perfluorinated Vinyl Ethers

Polymerizations of perfluorinated vinyl ethers (PFVEs) provide an important category of fluoropolymers that have received considerable interests in applications. In this work, we report the development of an organocatalyzed controlled radical alternating terpolymerization of PFVEs and vinyl ethers (VEs) under visible-light irradiation. This method not only enables the synthesis of a broad scope of fluorinated terpolymers of low dispersities and high chain-end fidelity, facilitating tuning the chemical compositions by rationally choosing the type and/or ratio of comonomers, but also allows temporal control of chain-growth, as well as the preparation of a variety of novel fluorinated block copolymers. To showcase the versatility of this method, fluorinated alternating terpolymers have been synthesized and customized to simultaneously display a variety of desirable properties for solid polymer electrolyte design, creating new opportunities in high-performance energy storage devices.

Synthesis of Polymer Brushes Via SI-PET-RAFT for Photodynamic Inactivation of Bacteria

Biofilms are a persistent issue in healthcare and industry. Once formed, the eradication of biofilms is challenging as the extracellular polymeric matrix provides protection against harsh environmental conditions and physically enhances resistance to antimicrobials. The fabrication of polymer brush coatings provides a versatile approach to modify the surface to resist the formation of biofilms. Herein, the authors report a facile synthetic route for the preparation of surface-tethered polymeric brushes with antifouling and visible light activated bactericidal properties using surface-initiated photoinduced electron transfer-reversible addition-fragmentation chain transfer polymerization (SI-PET-RAFT). Bactericidal property via the generation of singlet oxygen, which can be temporally and spatially controlled, is investigated against both Gram-positive and Gram-negative bacteria. In addition, the antibacterial properties of the surface can be recycled. This work paves the way for the preparation of polymer films that can resist and kill bacterial biofilms.

Solvent-Free Synthesis of the Polymer Electrolyte via Photo-Controlled Radical Polymerization: Toward Ultrafast In-Built Fabrication of Solid-State Batteries under Visible Light

Thin solid polymer electrolytes (SPEs) with good processability, improved room-temperature ionic conductivity, and better interfacial compatibility are urgently needed to develop solid-state batteries without safety and leakage issues. In-built electrolyte polymerization has emerged as a novel and effective platform to obtain such electrolytes. However, existing in-built methods usually involve heat, UV, γ irradiation, and so forth to initiate the polymerization and often require the addition of solvents to avoid the concentrated active propagating species, which inevitably afford solvent residues that persist in the electrolyte matrix, leading to complex SPE preparation processes, safety hazards, and side reactions with the electrodes. Herein, a simple solvent-free preparation of the poly(mPEGAA)-based electrolyte film was achieved via the photo-controlled radical polymerization under visible light irradiation via an in-built manner, which resulted in 99% monomer conversion within 5 min to obtain the polymer electrolytes with a controlled molecular weight distribution. Thanks to the mild and green conditions, a thin, solvent-free, and cross-linked SPE electrolyte film was obtained efficiently yet in a well-regulated manner, which gave rise to good interfacial compatibility and an improved room-temperature ionic conductivity of 1.5 × 10^-4 S cm^-1 at 25 °C. As-prepared solid-state LiFePO₄|Li batteries based on the in-built thin SPE exhibited a high discharge areal capacity of 1.7 mA h cm^-2 (164.6 mA h g^-1) at an ambient temperature. Furthermore, the system displayed lithium dendrite suppression behavior and good long-term charge-discharge cycling in the Li symmetric battery for over 270 h, representing enhanced stability and capacities compared with ex-built systems.