One-Pot Synthesis of Hyperbranched Polymers via Visible Light Regulated Switchable Catalysis

Abstract

Switchable catalysis promises exceptional efficiency in synthesizing polymers with ever-increasing structural complexity. However, current achievements in such attempts are limited to constructing linear block copolymers. Here we report a visible light regulated switchable catalytic system capable of synthesizing hyperbranched polymers in a one-pot/two-stage procedure with commercial glycidyl acrylate (GA) as a heterofunctional monomer. Using (salen)CoIIICl (1) as the catalyst, the ring-opening reaction under a carbon monoxide atmosphere occurs with high regioselectivity (> 99% at the methylene position), providing an alkoxycarbonyl cobalt acrylate intermediate (2a) during the first stage. Upon exposure to light, the reaction enters the second stage, wherein 2a serves as a polymerizable initiator for organometallic-mediated radical self-condensing vinyl polymerization (OMR-SCVP). Given the organocobalt chain-end functionality of the resulting hyperbranched poly(glycidyl acrylate) (hb-PGA), a further chain extension process gives access to a core-shell copolymer with brush-on-hyperbranched arm architecture. Notably, the post-modification with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) affords a metal-free hb-PGA that simultaneously improves the toughness and glass transition temperature of epoxy thermosets, while maintaining their storage modulus.

Switchable copolymerization of mixed monomers catalyzed by imidazolium ionic liquids

“…20,21 Although significant advances have been made in block polymer synthesis, it remains a key challenge to form various architectures with switchable copolymerization from monomer mixtures. [22][23][24][25] Copolymerization with sequential transformation is of long-standing interest as a means to control polymer composition from mixed monomers, which can be developed with a switchable catalysis process between different catalytic cycles. 26 Polyesters are one of the most attractive polymers with good biodegradability and biocompatibility, which can be prepared via a controlled route including ring-opening copolymerization (ROCOP) of anhydrides/epoxides and ring-opening polymerization (ROP) of lactones under mild conditions.…”

Near-Infrared Light and Acid/Base Dual-Regulated Polymerization Utilizing Imidazole-Anion-Fused Perylene Diimides as Photocatalysts

“…The growth of macromolecules in organisms is stimulated by specific triggers. , In an effort to simulate this natural process, researchers have sought to regulate polymerization “on” and “off” on demand by utilizing external stimuli. − This has opened a new way to exert spatial and temporal control over polymerization and, moreover, increase complexity of the polymer architecture and microstructure. − The development of physical- or chemical-switchable catalysts has garnered most attention. − However, current state-of-the-art catalysts rely primarily on single stimulus including temperature, , pH, − light, − applied voltage, , mechanical force, − or chemical reagents. , There is a scarcity of “biolike” polymerization that can be regulated by dual or multiple stimuli. − …”