Gao Yunxiang, Islam Mohammad Tarequl, Otuokere Promise Uzoamaka, Pulikkathara Merlyn, Liu Yuemin
Department of Chemistry and Physics, Prairie View A&M University, Prairie View, TX 77446, USA.
Nanomaterials (Basel). 2024 Sep 9;14(17):1464. doi: 10.3390/nano14171464.
Carbon nanotubes (CNTs) are often regarded as semi-rigid, all-carbon polymers. However, unlike conventional polymers that can form 3D networks such as hydrogels or elastomers through crosslinking in solution, CNTs have long been considered non-crosslinkable under mild conditions. This perception changed with our recent discovery of UV-defluorination-driven direct crosslinking of CNTs in solution. In this study, we further investigate the thermal stability of UV-defluorination-driven crosslinked CNTs, revealing that they are metastable and decompose more readily than either pristine or fluorinated CNTs under Raman laser irradiation. Using Raman spectroscopy under controlled laser power, we examined both single-walled and multi-walled fluorinated CNTs. The results demonstrate that UV-defluorinated CNTs exhibit reduced thermal stability compared to their pristine or untreated fluorinated counterparts. This instability is attributed to the strain on the intertube crosslinking bonds resulting from the curved carbon lattice of the linked CNTs. The metallic CNTs in the crosslinked CNT networks decompose and revert to their pristine state more readily than the semiconducting ones. The inherent instability of crosslinked CNTs leads to combustion at temperatures approximately 100 °C lower than those required for non-crosslinked fluorinated CNTs. This property positions crosslinked CNTs as promising candidates for applications where mechanically robust, lightweight materials are needed, along with feasible post-use removal options.
碳纳米管（CNTs）通常被视为半刚性的全碳聚合物。然而，与传统聚合物不同，传统聚合物可通过在溶液中交联形成三维网络，如水凝胶或弹性体，长期以来人们一直认为碳纳米管在温和条件下不可交联。随着我们最近发现溶液中紫外线脱氟驱动的碳纳米管直接交联，这种观念发生了改变。在本研究中，我们进一步研究了紫外线脱氟驱动交联的碳纳米管的热稳定性，发现它们是亚稳态的，并且在拉曼激光照射下比原始或氟化的碳纳米管更容易分解。在可控激光功率下使用拉曼光谱，我们研究了单壁和多壁氟化碳纳米管。结果表明，与原始或未处理的氟化碳纳米管相比，紫外线脱氟的碳纳米管热稳定性降低。这种不稳定性归因于连接的碳纳米管弯曲碳晶格导致的管间交联键上的应变。交联碳纳米管网络中的金属碳纳米管比半导体碳纳米管更容易分解并恢复到原始状态。交联碳纳米管固有的不稳定性导致其在比未交联的氟化碳纳米管所需温度低约100°C的温度下燃烧。这一特性使交联碳纳米管成为需要机械坚固、轻质材料以及可行的使用后去除方案的应用的有前途的候选材料。
