Ionic Liquids Inspiring the Design of Charged Polymers: The Allure of Phosphorus

Ionomers and polyelectrolytes represent families of macromolecules that incorporate cationic or anionic sites either pendant or within the polymer main chain. These charged compositions enable tunable physical properties such as ionic conductivity, thermal and chemical stability, water transport, and anion exchange capability. Ion-containing polymers are versatile materials that continuously enable emerging technologies such as water purification, gas separation, gene delivery, biosensors, fuel cells, and electro-mechanical devices. Ionic liquids continue to inspire the design of new families of ionomers and polyelectrolytes. This lecture will present a library of novel monomer strategies wherein the monomers are tailored with a nitrogen or phosphorous site that is capable of efficient alkylation either using a functional monomer strategy or post-polymerization modification. Living anionic and controlled radical polymerization methods enable the preparation of diverse families of ammonium, imidazolium, and phosphonium containing block copolymers, where the placement of the charged site in a low glass transition temperature sequence provides superior performance. The role of block copolymer morphology is critical in determining both water and ion transport properties. The lecture will also highlight an unprecedented step-growth polymerization process leading to a new family of melt processable phosphonium based ionenes whose diversity is further enriched upon anion exchange to finely tune thermomechanical and rheological performance. The design of charge containing polymers relative to tailored hydrogen bonding sites will be presented, and recent advances in nucleobase-containing acrylates will exemplify potential synergies. The impact of novel multiphase, hydrogen bond and ion-containing polymeric systems on adhesion, electro-active membranes, drug delivery, and 3D printing will be discussed.