Hierarchical Porosity in Emulsion-Templated, Porogen-Containing Interpenetrating Polymer Networks: Hyper-Cross-Linking and Carbonization

Hierarchically porous polymers combine microporosity, mesoporosity, and macroporosity to enhance pore accessibility and transport. This work describes generating hierarchically porous polymers and carbons derived therefrom by combining emulsion-templated macroporous polymers bearing novel macromolecular structures with simultaneous Friedel-Crafts hyper-cross-linking and porogen removal. The hyper-cross-linking was based on a copolymer of vinylbenzyl chloride and divinylbenzene, while the porogen was based on poly(ϵ-caprolactone) (PCL). The two polymer systems were combined using one-pot syntheses of either simultaneous interpenetrating polymer networks (IPNs) containing a PCL-based poly(urethane urea) (PUU) or a PCL-based semi-IPN. In the semi-IPN, the microporosity was enhanced through hyper-cross-linking and through porogen removal during carbonization. The effects of incorporating a PCL-based PUU depended upon the diisocyanate. Unexpectedly, mesoporosity was generated from hyper-cross-linking an IPN synthesized with an aliphatic diisocyanate. On the other hand, the formation of interconnected networks from hyper-cross-linking an IPN synthesized with an aromatic diisocyanate enhanced both the microporosity and thermal stability.