Polymer Nanoencapsulated Mesoporous Vanadia with Unusual Ductility at Cryogenic Temperatures
An aerogel-like composite material was synthesized by casting a conformal 4-6 nm diisocyanatederived polymer coating on the bird-nest like skeletal framework of mesoporous vanadia consisting of entangled 100-200 nm long, 30-40 nm thick worm-like objects. The new material does not fail even under high strain compression (>90%) and maintains a highly unusual ductility at cryogenic temperatures (-196 deg C). by comparison, nanoparticulate silica crosslinked with the same polymer at the same bulk density (~0.45 g cm^-3) behaves as a typical polymer and metal, showing brittle behavior as the temperature decreases. The high strength of nanoencapsulated vanadia is attributed to interlocking of the skeletal nanoworms, and the high ductility at cryogenic temperatures to sintering-like melting and fusion of their polymer coating under compression.
N. Leventis and L. Sotiriou-Leventis and J. Schnobrich and H. Luo and H. Lu and S. Mulik and G. Churu and A. Dass and E. F. Fabrizio and A. Hobbs, "Polymer Nanoencapsulated Mesoporous Vanadia with Unusual Ductility at Cryogenic Temperatures," Journal of Materials Chemistry, Royal Society of Chemistry, Mar 2008.
The definitive version is available at http://dx.doi.org/10.1039/b801770k
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