Simultaneous Emulsion Templating and Foaming of a Renewable Resource Monomer: Urethanes, Ureas, and Amides

High Resolution Image Download MS PowerPoint Slide Low-density polymers with micrometer-scale porosities can be generated using the internal phases of high internal phase emulsions (HIPEs) as templates. The combination of polyols and polyisocyanates in the external phases of water-in-oil emulsions has been used to synthesize poly(urethane urea) polyHIPEs where the isocyanate–water reaction generates urea and releases CO 2 . Low-density polymer foams with millimeter-scale porosities can be generated using this same urea reaction. Here, emulsion templating was combined with foaming using an innovative one-pot, one-stage synthesis based on hexamethylene diisocyanate, castor oil, and carboxylic acids to produce poly(urethane urea amides) with hierarchical porosities and densities of ∼0.07 g/cm 3 . Unexpectedly, the extensive foaming at room temperature in the presence of carboxylic acids seemed to promote the urethane reaction at the expense of the urea and amide reactions, producing more elastomeric polymers. These results provide the foundations for generating foamed emulsion-templated polyHIPEs with predesigned macromolecular structures, hierarchically porous structures, and properties.