biostudies-literatureXu MNational Natural Science Foundation of China (National Science Foundation of China)265https://www.ebi.ac.uk/biostudies/studies/S-EPMC12783137biostudies-literatureUnknown17(1)Ethylene-based crystalline copolymers are important materials across broad applications. However, precise control over their primary structures remains a critical challenge in advancing functional materials, limited by the intrinsic reactivity difference between ethylene and comonomers. In this work, we report the development of a light-driven organocatalyzed reversible-deactivation radical copolymerization to access well-defined ethylene-chlorotrifluoroethylene copolymer (ECTFE) under mild conditions (<5 atm, 25 °C). The rational design of a three-armed phenothiazine catalyst in combination with a fluorinated dithiocarbamate furnishes good chain-growth control in the photoredox-mediated copolymerization, yielding ECTFE of excellent alternating sequence with minimized chain defects, which resulted in high crystallinity and superior melting points (up to 263.8 °C). Importantly, the obtained ECTFE exhibits outstanding chain-end activity/fidelity, enabling chain-extension (co)polymerization to access a variety of unprecedented ECTFE-based block copolymers upon visible-light exposure, which has successfully integrated rigid and soft blocks in single chains. The ease of synthesizing such block copolymers creates a versatile and convenient platform to largely tune mechanical properties, affording polymeric materials spanning from thermoplastics to elastomers via structural tailoring.Nature communicationsPhotoredox-controlled alternating copolymerization enables highly crystalline structures and block copolymers from thermoplastic to elastomer.PMC12783137no. 22425103no. 22171051Chen QXu MChen KGuo XChen MHan SfalsePhotoredox-controlled alternating copolymerization enables highly crystalline structures and block copolymers from thermoplastic to elastomer.Ethylene-based crystalline copolymers are important materials across broad applications. However, precise control over their primary structures remains a critical challenge in advancing functional materials, limited by the intrinsic reactivity difference between ethylene and comonomers. In this work, we report the development of a light-driven organocatalyzed reversible-deactivation radical copolymerization to access well-defined ethylene-chlorotrifluoroethylene copolymer (ECTFE) under mild conditions (<5 atm, 25 °C). The rational design of a three-armed phenothiazine catalyst in combination with a fluorinated dithiocarbamate furnishes good chain-growth control in the photoredox-mediated copolymerization, yielding ECTFE of excellent alternating sequence with minimized chain defects, which resulted in high crystallinity and superior melting points (up to 263.8 °C). Importantly, the obtained ECTFE exhibits outstanding chain-end activity/fidelity, enabling chain-extension (co)polymerization to access a variety of unprecedented ECTFE-based block copolymers upon visible-light exposure, which has successfully integrated rigid and soft blocks in single chains. The ease of synthesizing such block copolymers creates a versatile and convenient platform to largely tune mechanical properties, affording polymeric materials spanning from thermoplastics to elastomers via structural tailoring.2025-01-01T00:00:00Z2025 Dec2026-06-06T13:08:43.512Z2026-05-30T03:11:42.278ZS-EPMC127831374138802710.1038/s41467-025-66962-8