Modifying the softening point (SP) of pitch is crucial owing to its substantial influence on pitch applicability. This study presents a novel fluorination technique for engineering the SP of mesophase pitch (MP). Low-concentration fluorine gas was used to modify the edge sites of the MP, allowing for either an increase or decrease in the SP by controlling the gas reactivity. The fluorination was conducted with 20 vol% F2 gas under reaction temperature of 25, 50, and 75 ℃ for 2 h in atmospheric pressure. A reduction in SP was achieved through edge alkylation, with a decrease of up to 14.1% observed after the fluorination. Conversely, an increase in SP resulted from edge dealkylation at higher reaction temperatures. As the modified MPs retained perfect anisotropy, this study offers an effective strategy for adjusting the SP to meet application needs without causing structural deterioration.

Controlling the softening point of mesophase pitch via edge-selective fluorination
    Abstract
    1 Introduction
    2 Experimental
        2.1 Fluorination of MP
        2.2 Characterization of fluorine-treated MP
    3 Results and discussion
    4 Conclusion
    References

• Chaehun Lim(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea)
• Seongjae Myeong(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea)
• Sangyeop Lee(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea)
• Seongmin Ha(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea)
• Young‑Seak Lee(Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 34134, Republic of Korea, Institute of Carbon Fusion Technology (InCFT), Chungnam National University, Daejeon 34134, Republic of Korea) Corresponding author