关键词: 热缩聚, 中间相, 模型化合物, 含五元环的芳烃, 扩环反应

Abstract: Thermal polycondensation experiments were conducted on fluorene and phenanthrene. The microcrystalline structures of the polycondensation products of phenanthrene and fluorene were analyzed by means of polarizing microscopy, X-ray diffraction, Raman spectroscopy, and infrared spectroscopy. The results showed that the microcrystalline structure of the polycondensation products of phenanthrene was superior to that of fluorene in terms of arrangement regularity, degree of polycondensation, and microcrystalline size. Five model compounds, namely indene, indan, fluorene, 9,9-dimethylfluorene, and fluoranthene, were selected for the thermal polycondensation experiments. The composition and molecular structure of the gas-liquid product were analyzed by gas chromatography and gas chromatography-mass spectrometry. The results indicated that the quinary rings in indan, indene, fluorene, and 9,9-dimethylfluorene had the potential for ring expansion. Moreover, the ring expansion phenomenon of 9,9-dimethylfluorene was particularly pronounced. To investigate the reasons for the ring expansion phenomenon of 9,9-dimethylfluorene, a certain proportion of olefins was added to indan, fluorene, and fluoranthene. The results showed that its ring expansion selectivity was significantly improved, highlighting the crucial importance of an additional carbon source for the ring expansion reaction.

Key words: thermal polycondensation, mesophase, model compound, aromatic hydrocarbons containing quinary rings, ring expansion reaction