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Millimeter-Size Spherical Polyurea Aerogel Beads with Narrow Size Distribution

Laboratory of Inorganic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece
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Received: 3 July 2018 / Revised: 30 July 2018 / Accepted: 3 August 2018 / Published: 6 August 2018
(This article belongs to the Special Issue Aerogels 2018)
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We report the room temperature synthesis of spherical millimeter-size polyurea (PUA) aerogel beads. Wet-gels of said beads were obtained by dripping a propylene carbonate solution of an aliphatic triisocyanate based on isocyanurate nodes into a mixture of ethylenediamine and heavy mineral oil. Drying the resulting wet spherical gels with supercritical fluid (SCF) CO2 afforded spherical aerogel beads with a mean diameter of 2.7 mm, and a narrow size distribution (full width at half maximum: 0.4 mm). Spherical PUA aerogel beads had low density (0.166 ± 0.001 g cm–3), high porosity (87% v/v) and high surface area (197 m2 g–1). IR, 1H magic angle spinning (MAS) and 13C cross-polarization magic angle spinning (CPMAS) NMR showed the characteristic peaks of urea and the isocyanurate ring. Scanning electron microscopy (SEM) showed the presence of a thin, yet porous skin on the surface of the beads with a different (denser) morphology than their interior. The synthetic method shown here is simple, cost-efficient and suitable for large-scale production of PUA aerogel beads. View Full-Text
Keywords: aerogels; Desmodur N3300; ethylenediamine; polyurea; spherical beads aerogels; Desmodur N3300; ethylenediamine; polyurea; spherical beads

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Chriti, D.; Raptopoulos, G.; Papastergiou, M.; Paraskevopoulou, P. Millimeter-Size Spherical Polyurea Aerogel Beads with Narrow Size Distribution. Gels 2018, 4, 66.

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