Thermal Anisotropy Ratio >1000 in Solution-Spun Macroscopic Carbon Nanotube Films.
basic_science · Level V
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- Record sourced from PubMed, PMID 42287244.
- Also identified by DOI 10.1021/acs.nanolett.6c00663.
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Abstract
Films with large anisotropy ratios (<i>r</i>) between the in-plane and cross-plane thermal conductivity (κ) can be used for directional heat spreading in electronics thermal management. Here, we show that commercially available solution-spun carbon nanotube (CNT) films with 20 μm thickness and centimeter-scale lateral dimensions exhibit orthotropic thermal conductivity with the highest reported <i>r</i> to date, reaching <i>r</i> = 1400 ± 160 at room temperature (<i>T</i>). We find <i>r</i> using laser flash thermal diffusivity (α) measurements over a <i>T</i> range from 198 to 573 K. Dedoping of acid residuals via annealing increases the in-plane-aligned α<sub><i>x</i></sub> of dedoped samples by a factor of 2 compared to the doped samples. These dedoped CNT films also display a strong α<sub><i>x</i></sub> ∝ <i>T</i><sup>-1.1</sup> scaling, indicating that phonon-phonon scattering impacts heat transport along the direction of alignment. Our work motivates further exploration of ultrahigh <i>r</i> in macroscopic CNT materials and applications of CNT films for directional heat spreading.