Modulus-density scaling behaviour and framework architecture of nanoporous self-assembled silicas

Hongyou Fan, Christopher Hartshorn, Thomas Buchheit, David Tallant, Roger Assink, Regina Simpson, Dave J. Kissel, Daniel J. Lacks, Salvatore Torquato, C. Jeffrey Brinker

Research output: Contribution to journalArticle

128 Scopus citations

Abstract

Natural porous materials such as bone, wood and pith evolved to maximize modulus for a given density. For these three-dimensional cellular solids, modulus scales quadratically with relative density. But can nanostructuring improve on Nature's designs? Here, we report modulus-density scaling relationships for cubic (C), hexagonal (H) and worm-like disordered (D) nanoporous silicas prepared by surfactant-directed self-assembly. Over the relative density range, 0.5 to 0.65, Young's modulus scales as (density)n where n(C)<n(H)<n(D)<2, indicating that nanostructured porous silicas exhibit a structure-specific hierarchy of modulus values D<H<C. Scaling exponents less than 2 emphasize that the moduli are less sensitive to porosity than those of natural cellular solids, which possess extremal moduli based on linear elasticity theory. Using molecular modelling and Raman and NMR spectroscopy, we show that uniform nanoscale confinement causes the silica framework of self-assembled silica to contain a higher portion of small, stiff rings than found in other forms of amorphous silica. The nanostructure-specific hierarchy and systematic increase in framework modulus we observe, when decreasing the silica framework thickness below 2 nm, provides a new ability to maximize mechanical properties at a given density needed for nanoporous materials integration.

Original languageEnglish (US)
Pages (from-to)418-423
Number of pages6
JournalNature Materials
Volume6
Issue number6
DOIs
StatePublished - Jun 2007

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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    Fan, H., Hartshorn, C., Buchheit, T., Tallant, D., Assink, R., Simpson, R., Kissel, D. J., Lacks, D. J., Torquato, S., & Brinker, C. J. (2007). Modulus-density scaling behaviour and framework architecture of nanoporous self-assembled silicas. Nature Materials, 6(6), 418-423. https://doi.org/10.1038/nmat1913