One-dimensional carbon nanotube (CNT) exhibits excellent mechanical properties and is considered to be an ideal candidate material for the space elevator. However, subtle changes in its chirality strongly affect its physical and chemical properties, including mechanical properties (such as Young's modulus, YM). Theoretical studies reveal that the YMs of perfect single-walled carbon nanotubes (SWCNTs) are in the order of TPa and related to their structures. Nevertheless, due to the lack of SWCNTs samples with well-defined structures and the difficulties in mechanical tests on individual SWCNTs, the theoretical correlations between YM and structure of SWCNTs have not been verified and are still in debate, which directly influences the practical utilization of the excellent mechanical properties of SWCNTs. In this work, we have developed an experimental method to measure the YM of an individual micrometer-scale suspended CNT by atomic force microscopy. A distinct regularity is found between the YM and chirality (i.e., chiral angle and diameter) of SWCNT in the experiment for the first time. By comparing the YMs of SWCNTs with similar diameters and different chiral angles, it manifests that the SWCNT with a near zigzag configuration has a larger YM. This finding suggests that the effect of SWCNT’s structures on the YMs cannot be ignored. The developed method of measuring YMs of SWCNTs will be valuable for further experimental research on the inherent physical and chemical properties of SWCNTs.

Despite the ever-increasing demand of nanofillers for thermal enhancement of polymer composites with higher thermal conductivity and irregular geometry, nanomaterials like carbon nanotubes (CNTs) have been constrained by the nonuniform dispersion and difficulty in constructing effective three-dimensional (3D) conduction network with low loading and desired isotropic or anisotropic (specific preferred heat conduction) performances. Herein, we illustrated the in-situ construction of CNT based 3D heat conduction networks with different directional performances. First, to in-situ construct an isotropic percolated conduction network, with spherical cores as support materials, we developed a confined-growth technique for CNT-core sea urchin (CNTSU) materials. With 21.0 wt.% CNTSU loading, the thermal conductivity of composites reached 1.43 ± 0.13 W/(m·K). Secondly, with aligned hexagonal boron nitride (hBN) as an anisotropic support, we constructed CNT-hBN aligned networks by in-situ CNT growth, which improved the utilization efficiency of high density hBN and reduced the thermal interface resistance between matrix and fillers. With ~ 8.5 wt.% loading, the composites possess thermal conductivity up to 0.86 ± 0.14 W/(m·K), 374% of that for neat matrix. Due to the uniformity of CNTs in hBN network, the synergistic thermal enhancement from one-dimensional (1D) + two-dimensional (2D) hybrid materials becomes more distinct. Based on the detailed experimental evidence, the importance of purposeful production of a uniformly interconnected heat conduction 3D network with desired directional performance can be observed, particularly compared with the traditional direct-mixing method. This study opens new possibilities for the preparation of high-power-density electronics packaging and interfacial materials when both directional thermal performance and complex composite geometry are simultaneously required.