sp-sp2杂化碳基材料的简易合成及表征

Synthesis and characterization of sp-sp2 hybrid carbon materials

  • 摘要: 在室温下通过简易的有机偶联聚合反应得到了具有sp-sp2杂化结构的多孔碳基聚合物,通过对聚合产物简单的热处理得到了有较高比表面积的多孔碳基材料。采用比表面积分析仪、扫描电镜、拉曼光谱仪等对聚合物热处理前后的孔分布、形貌、拉曼峰等进行了分析表征,发现低聚体混合物在聚合后成为具有墨水瓶型孔的多孔碳基聚合物材料且在热处理后仍保持墨水瓶型孔的结构。在采用模板法进行聚合时,在聚合产物的透射电镜照片和选区衍射图中发现了类似二维材料的形貌和衍射谱图,这为采用模板法合成全新的sp-sp2杂化的二维碳的同素异形体石墨炔提供了实验基础。

     

    Abstract: A 1,3,5-trichloro-2,4,6-triethinyl-benzene monomer was synthesized from 1,3,5-trichlorobenzene by iodination with periodic acid, followed by the substitution of iodine with trimethylsilylacetylene and finally the removal of the trimethylsilyl groups with tetrabutylammonium fluoride by the Sonogashira reaction. It was polymerized in pyridine under the catalysis of Cu+ to produce a gel-like polymer that was freeze-dried to give a 3D sp-sp2 hybrid carbon material. A 2D sp-sp2 hybrid carbon material was also made on a copper substrate which acted as both catalyst and template by first pretreating the substrate with a HCl solution,then soaking the substrate in pyridine, slowly adding a low concentration solution of 1,3,5-trichloro-2,4,6-triethinyl-benzene in pyridine,keeping it at 60 ℃ for 72 h for polymerization, rinsing the substrate consecutively with pyridine,dimethylformamide,dimethyl sulfoxide and acetone, and finally removing the substrate by FeCl3 etching. The substituted intermediate from the first reaction, 1,3,5-trichloro-2,4,6-tri(trimethylsilylacetyl)-benzene, was stored in ether at ambient temperature for one month to yield a black solid of oligomers. Results indicated that the 3D sp-sp2 hybrid carbon material consisted of carbon, chlorine and oxygen, whose composition, after oxygen was subtracted, was the same as that of the monomer. It had Raman peaks consistent with graphdiyne, and a BET surface area of 334 m2/g with a Ⅰ-Ⅱ type isotherm with a H3 hysteresis loop. The presence of a 2D graphyne-like structure was identified by HRTEM and selected area diffraction for the sp-sp2 hybrid carbon on the copper substrate,indicating that it is possible for chemical synthesis of 2D graphyne by a template method. The black solid of oligomers consisted of mainly carbon,silicon and chlorine, which had a BET surface area of 382 m2/g with an ink-bottle pore texture. After it was annealed at 650 ℃ for 6 h, the chlorine was mostly eliminated, the silicon content decreased significantly and the intensities of the D and G peaks increased while the peak at 2 200 cm-1 ascribed to graphyne disappeared producing a micro/mesoporous carbon with a surface area of 896 m2/g, an ink-bottle pore texture and pore sizes less than 30 nm, indicating that the graphyne-like structure was destroyed.

     

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