CRCU

Chemical Research in Chinese Universities ›› 2019, Vol. 35 ›› Issue (1): 157-162.doi: 10.1007/s40242-019-8159-9

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In situ Characterization of Phase Transition of Amorphous Poly(9,9-di-n-octyl-2,7-fluorene) Thin Film During Thermal Annealing

MENG Shengfei1,2, WANG Pengyue2, CHEN Liuran2, GAO Guanghui1, ZHANG Jidong2   

  1. 1. School of Chemical Engineering and Advanced Institute of Materials Science, Changchun University of Technology, Changchun 130012, P. R. China;
    2. State Key Lab of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
  • Received:2018-05-14 Revised:2018-11-14 Online:2019-02-01 Published:2018-12-05
  • Contact: GAO Guanghui, ZHANG Jidong E-mail:ghgao@ccut.edu.cn;jdzhang@ciac.ac.cn
  • Supported by:
    Supported by the Science Foundation of the Chinese Acadeny of Sciences, China(No.Y8228021001) and the National Natural Science Foundation of China(No.5187030513).

Abstract: Amorphous poly (9, 9-di-n-octyl-2, 7-fluorene) (PFO) thin films were characterized in situ via thermal annealing based on grazing incidence X-ray diffraction (GIXRD) profiles, UV-visible absorption spectrophotometry, and Fourier transform infrared spectroscopy (FTIR). The results of GIXRD indicated that the amorphous phase transformed into a crystalline phase when the annealing temperature was higher than 80℃. Different outcomes were elicited for the intensities and d-spacings of the diffraction peaks below and above 80℃, which were attributed to the formation of the k-phase. The mechanism of phase transition was revealed by in situ UV-visible absorption and FTIR spectra, whereby the rearrangement of the side chains was dominant and the movement of the main chains was minimal, even when the annealing temperature was lower than 80℃. In contrast, the rearrangement of the main chains was dominant when the temperature was higher than 80℃.

Key words: Polyfluorene, Phase transition, Thermal annealing, Liquid crystalline k-phase