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

• DOI: 10.1021/acsami.8b06604
• Publication Date: 2018-06-06T14:45:51Z
• Authors: Jurn Heinen; Austin D. Ready; Thomas D. Bennett; David Dubbeldam; Raymond W. Friddle; Nicholas C. Burtch
• Keywords: Negative Thermal Expansion

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