Mechanochemical Synthesis of Ionic Polymers: Solid-State Ball-Milling Polymerization for Unrestricted Solubility Enabling Copolymerization of Immiscible Monomers
Gue Seon Lee, Hyun Sub Lee, Nuri Kim, Hyun Gyu Shin, Yun Ha Hwang, Seung Jae Lee, Jeung Gon Kim
Abstract
This study demonstrates the facile synthesis of ionic polymers using a solid-state mechanochemical ball milling method, which offers a straightforward, ecofriendly, and broad scope compared to conventional solution polymerization techniques. Unlike solution polymerization, which is limited by solvent selection and often results in poor efficiency, direct ball-milling polymerization enables the production of the desired product polymers from a broader range of ionic monomers without solubility and miscibility constraints. We employed free-radical polymerization of styrene and (meth)acrylic ionic monomers, as well as Ru-initiated ring-opening metathesis polymerization of norbornenyl ionic monomers, to demonstrate the effectiveness of the mechanochemical approach. Additionally, the study explored the mechanochemical copolymerization of immiscible monomer pairs such as sodium carboxylate/pyrene and ammonium sulfone betaine/porphyrin moieties, producing water-soluble porphyrin and pyrene polymers. Overall, this research showcases mechanochemistry’s versatility and efficiency in synthesizing ionic polymers, anticipating its use in various applications.