Elucidating the Variable-Temperature Mechanical Properties of a Negative Thermal Expansion Metal–Organic Framework

• Published in: ACS applied materials & interfaces 2018-06, Vol.10 (25), p.21079-21083
• Main Authors: Heinen, Jurn, Ready, Austin D, Bennett, Thomas D, Dubbeldam, David, Friddle, Raymond W, Burtch, Nicholas C
• Format: Article
• Language: English
• Subjects: dynamic mechanical analysis; elasticity; HKUST-1; MATERIALS SCIENCE; mechanical properties; metal−organic frameworks; molecular dynamics; nanoindentations; negative thermal expansion
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.8b06604

We report the first experimental study into the thermomechanical and viscoelastic properties of a metal–organic framework (MOF) material. Nanoindentations show a decrease in the Young’s modulus, consistent with classical molecular dynamics simulations, and hardness of HKUST-1 with increasing temperature over the 25–100 °C range. Variable-temperature dynamic mechanical analysis reveals significant creep behavior, with a reduction of 56% and 88% of the hardness over 10 min at 25 and 100 °C, respectively. This result suggests that, despite the increased density that results from increasing temperature in the negative thermal expansion MOF, the thermally induced softening due to vibrational and entropic contributions plays a more dominant role in dictating the material’s temperature-dependent mechanical behavior.