Fabrication of emulsion-templated open-cell polymethacrylimide foam

In this work, the emulsion-templating technique is proposed to fabricate polymethacrylimide (PMI) foam for the first time. Different from those PMI foam reported in the literature, having a closed-cell structure with submillimeter-sized voids, the emulsion-templated PMI foam has an obvious open-cell structure with micrometer-sized voids. The pore structure, density, and porosity of the PMI foam herein could be tuned by simply changing the internal phase volume fraction and/or the surfactant concentration of the emulsion template. The density of PMI foam is varied between 0.174 and 0.350 g·cm⁻³. The prepared PMI foam exhibited excellent mechanical properties, the compressive strength and compressive modulus ranged from 4.87 to 7.48 MPa and from 58.67 to 124.67 MPa, respectively, which are both much higher than the traditional closed-cell PMI foams with similar density. The prepared PMI foam has excellent thermal resistance with its initial thermal decomposition temperature of 325°C in nitrogen and 253°C in air. The novel porous structure combined with its high strength and high heat resistance would expand the application of PMI foam.