Continuous Manufacturing of Aerogel-Foam Sheets and Films

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This grant will support research that contributes new knowledge on continuous manufacturing of meters long and tens of centimeter wide highly porous, polymer aerogel-foam sheets and films, thus advancing scientific understanding of materials fabrication and producing enabling technologies to serve national interests in defense, health, and energy. The aerogel-foam sheets will have coexisting open pores of several length scales that introduce new functions not achievable from conventional foam and aerogel materials obtained in current technologies. This award supports the research on avenues of introduction of open pores of multiple length scales in conjunction with high-speed fabrication of sheets and films. The new aerogel-foam sheets and films will be appropriate for fabrication of protective gears to combat nanoparticles and other bioactive agent intrusion into human body, as filter materials for removal of 10-200 nm size airborne nanoparticles, aerosols, and living organisms, as oil-water separation media, and as gel electrolyte separators to expand the temperature window of Li-ion batteries. The knowledge developed in this research will benefit several disciplines, such as textiles, electrochemistry, membrane separation, immunology, and manufacturing. The multi-disciplinary nature of the research will broaden participation of underrepresented groups in research and will positively impact engineering education. Aerogel-foams are lightweight materials that combine certain attributes of foams with those of aerogels. A population of micrometer size pores (macrovoids) introduced via oil-in-oil emulsion templating method inside inherently generated macro- and mesoporous networks of polymer aerogels make these materials attractive. Conventional aerogel articles do not contain macrovoids while conventional foaming technologies do not produce aerogels and cannot be adapted to produce aerogel foams. In this work, the macrovoids will be introduced in aerogel architecture via oil-in-oil emulsion-templating method in conjunction with a step-polymerization scheme that produces polyimide chains. In this context, the selection of surfactants and corresponding stability of the dispersed oil phase against coalescence and gelation kinetics of the continuous phase present several fundamental challenges that must be overcome to successfully manufacture meters long and tens of centimeter wide aerogel foam sheets and film specimens. The polarity of block copolymer type non-ionic surfactants, appropriate for obtaining stable oil-in-oil emulsions, will influence the polymer gelation kinetics and the openness of the macrovoid skin layers. The organic solvent of appropriate electron accepting ability will allow variation of gel times from 3 min to 3 h.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.