High-Pressure Synthesis of Carbon Nanothreads from Polycyclic Aromatic Hydrocarbons

Carbon nanothreads are one-dimensional sp3-hybridized polymers that have been theorized to exhibit new mechanical, thermal, or electronic properties. When derived from polycyclic aromatic hydrocarbons, nanothreads with thicker diameters emerge, which may promote higher ultimate strengths and/or bending moduli. In this contribution, we investigate the thermally mediated polymerization of naphthalene and pyrene under uniaxial pressure. Both PAHs undergo successful polymerizations, affording crystalline solids with distinctly different interplanar spacings (dNap = 7.77, 6.64, and 6.24 Å; dPy = 8.81, 8.37, and 7.33 Å). The application of heat resulted in the reduction of maximum pressures (at least 8 GPa for naphthalene and at least 4 GPa for pyrene), with a more well-defined diffraction pattern being obtained in the polymerization of pyrene. Spectroscopic analysis supported the formation of predominantly C(sp3)-hybridized extended carbon materials, consistent with simulated crystalline nanothreads without cross-linking.

碳纳米线（carbon nanothreads）是一类一维sp³杂化聚合物，理论上可展现出新颖的力学、热学或电学特性。当以多环芳烃（polycyclic aromatic hydrocarbons, PAHs）为前驱体制备时，可得到直径更粗的碳纳米线，此类纳米线有望具备更高的极限强度与/或弯曲模量。本研究针对单轴压力下热介导的萘与芘聚合过程展开探究。两种多环芳烃均成功发生聚合，得到具有显著差异层间距的结晶固体：萘对应的层间距（dNap）为7.77、6.64与6.24埃，芘对应的层间距（dPy）为8.81、8.37与7.33埃。加热可降低聚合所需的最大压力（萘至少需8 GPa，芘至少需4 GPa），且芘的聚合反应可得到峰形更规整、分辨率更高的衍射图谱。光谱分析结果证实，产物主要为sp³杂化的延展碳材料，与无交联的模拟结晶碳纳米线结构相符。