Ion-containing block copolymers continue to attract significant interest as conducting membranes in energy storage devices. Reversible addition−fragmentation chain transfer (RAFT) polymerization enables the synthesis of well-defined ionomeric A−BC−A triblock copolymers, featuring a microphase-separated morphology and a combination of excellent mechanical properties and high ion transport. The soft central "BC" block is composed of poly(4-styrenesulfonyl-(trifluoromethylsulfonyl)imide) (poly(Sty-Tf 2 N)) with −SO 2 −N − −SO 2 −CF 3 anionic groups associated with a mobile lithium cation and low-T g di(ethylene glycol)methyl ether methacrylate (DEGMEMA) units. External polystyrene A blocks provide mechanical strength with nanoscale morphology even at high ion content. Electrochemical impedance spectroscopy (EIS) and pulse-field-gradient (PFG) NMR spectroscopy have clarified the ion transport properties of these ionomeric A−BC−A triblock copolymers. Results confirmed that well-defined ionomeric A−BC−A triblock copolymers combine improved ion-transport properties with mechanical stability with significant potential for application in energy storage devices.

Photopolymerization coupled with mask projection microstereolithography successfully generated various 3D printed phosphonium polymerized ionic liquids (PILs) with low UV light intensity requirements and high digital resolution. Varying phosphonium monomer concentration, diacrylate cross-linking comonomer, and display images enabled precise 3D design and polymeric properties. The resulting cross-linked phosphonium PIL objects exhibited a synergy of high thermal stability, tunable glass transition temperature, optical clarity, and ion conductivity, which are collectively well-suited for emerging electro-active membrane technologies. Ion conductivity measurements on printed objects revealed a systematic progression in conductivity with ionic liquid monomer content, and thermal properties and solvent extraction demonstrated the formation of a polymerized ionic liquid network, with gel fractions exceeding 95%.

Abstract:The functionalization and cross-linking of polyethylene is synthetically challenging, commonly relying on highly optimized radical based postpolymerization strategies. To address these difficulties, a norbornene monomer containing Meldrum's acid is shown to be effectively copolymerized with polyethylene using a nickel R-iminocarbaxamidato complex, providing high-melting, semicrystalline polymers with a tunable incorporation of the functional comonomer. Upon heating the copolymer to common polyethylene processing temperatures, the thermolysis of Meldrum's acid to ketene provides the desired reactive group. This simple and versatile methodology does not require small molecule radical sources or catalysts, and the dimerization of the in situ generated ketenes is shown to provide tunable cross-linking densities in polyethylene. Subsequent rheological and tensile experiments illustrate the ability to tune cross-linked polyethylene properties by comonomer incorporation and elucidate valuable structure/property relationships in these materials. This study illustrates the power of well-defined and synthetically accessible functional groups in polyolefin synthesis and functionalization.