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It is well known that the recently developed photoinduced metal-free atom transfer radical polymerization (ATRP) has been considered as a promising methodology to completely eliminate transition metal residue in polymers. However, a serious problem needs to be improved, namely, large amount of organic photocatalysts should be used to keep the controllability over molecular weights and molecular weight distributions. In this work, a novel photocatalyst 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) with strong excited state reduction potential is successfully used to mediate a metal-free ATRP of methyl methacrylate just with parts per million (ppm) level usage under irradiation of blue light emitting diode at room temperature, using ethyl α-bromophenyl-acetate as a typical initiator with high initiator efficiency. The polymerization kinetic study, multiple controlled "on-off" light switching cycle regulation, and chain extension experiment confirm the "living"/controlled features of this promising photoinduced metal-free ATRP system with good molecular weight control in the presence of ppm level photocatalyst 4CzIPN.

Ultra‐high‐molecular‐weight (UHMW) polymers display outstanding properties and hold potential for wide applications. However, their precise synthesis remains challenging. Herein, we developed a novel reversible‐deactivation radical polymerization based on the strong and selective fluorine–fluorine interaction, allowing chain‐transfer agents to spontaneously differentiate into two groups that take charge of the chain growth and reversible deactivation of the growing chains, respectively. This method enables dramatically improved livingness of propagation, providing UHMW polymers with a surprisingly narrow molecular weight distribution (Đ≈1.1) from a variety of fluorinated (meth)acrylates and acrylamide at quantitative conversions under visible‐light irradiation. In situ chain‐end extensions from UHMW polymers facilitated the synthesis of well‐defined block copolymers, revealing the excellent chain‐end fidelity achieved by this method.

Polymer networks cross-linked by dynamic covalent bonds possess outstanding mechanical and rheological properties and are expected to be potential alternatives to conventional thermosets. However, while many recent studies of dynamically cross-linked thermosets focused on the employment of small molecular cross-linkers, the macro-cross-linking approach and the corresponding thermosets have been less demonstrated. In this work, reconfigurable and catalyst-free thermosets were synthesized by dynamic polymer–polymer interaction based on reversible boronic ester bond, providing simple and efficient access toward materials with improved mechanical strength and toughness in comparison to related commodity thermoplastics. The dynamic exchange of covalent bonds dispersed between polymer chains enables the materials to be malleable, recyclable, and healable under thermal conditions and readily processable with mechanical mixing without solvent. Moreover, the materials’ mechanical and rheological properties could be tuned by changing the cross-linking density. Although the dynamic networks exhibited good resistance against organic solvents, they could be cleaved as triggered by acids or diols and recycled through the de-cross-linking/re-cross-linking pathway. Given the dramatically increasing interest in environmentally sustainable materials, this polymer–polymer interaction mode provides a robust approach to engineering polymers with improved performance compared with the thermoplastic counterparts.

Continuous-flow chemistry represents a robust setting for photochemical reactions. We have developed the first computer-aided droplet-flow platform for photocontrolled radical polymerization. This method allows precise and scalable living polymerizations of monomers at high concentrations in flow, even when solids are generated. The consistent good performance of polymerization during the programmed change of reaction conditions demonstrates the reliability and utility of this method. Furthermore, the droplet-flow approach not only streamlines an automated high-throughput living polymerization (275 droplets of samples in 11 min), which enables the rapid generation of copolymer libraries for low-cost structure–property relationship screening, but also allows on-line switching to desirable reaction conditions for the scale-up (co)­polymerization purpose.

Polymerizations of perfluorinated vinyl ethers (PFVEs) providea ni mportant category of fluoropolymers that have received considerable interests in applications.Inthis 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 ab road scope of fluorinated terpolymers of lowdispersities and high chain-end fidelity,f acilitating tuning the chemical compositions by rationally choosing the type and/or ratio of comonomers,b ut also allows temporal control of chain-growth, as well as the preparation of avariety of novel fluorinated blockcopolymers. To showcase the versatility of this method, fluorinated alternating terpolymers have been synthesized and customized to simultaneously displayav ariety of desirable properties for solid polymer electrolyte design, creating new opportunities in high-performance energy storage devices.

Polyethylene (PE) is the most heavily used polymer worldwide. Considerable efforts have focused on modifying properties of PE via cross-linking. In contrast to previous crosslinking methods, which generate PE thermosets of low processability, here, we report the development of a dynamic covalent networking additive (DCNA) that possesses the PE backbone and reconfigurable network with alkyl boronic esters as novel dynamic linkages. The addition of DCNA at 5 wt % provides PE materials with clearly improved mechanical (e.g., tensile strength, Young's modulus, and yield strength) and rheological (e.g., creep resistance) properties at elevated temperatures. Moreover, the obtained materials could be easily reprocessed, recycled, and 3D-printed, creating opportunities toward sustainable and high-performance PE materials.

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