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    LIU Zhengyang, SHI Jinfeng, ZHAO Na, LI Zhibo. Preparation of Fluorine-Containing Polyethylsiloxane by Ring-Opening Polymerization of Cyclic Siloxanes Catalyzed by Phosphazene Base[J]. Journal of Functional Polymers, 2022, 35(5): 417-424. doi: 10.14133/j.cnki.1008-9357.20220105001
    Citation: LIU Zhengyang, SHI Jinfeng, ZHAO Na, LI Zhibo. Preparation of Fluorine-Containing Polyethylsiloxane by Ring-Opening Polymerization of Cyclic Siloxanes Catalyzed by Phosphazene Base[J]. Journal of Functional Polymers, 2022, 35(5): 417-424. doi: 10.14133/j.cnki.1008-9357.20220105001

    Preparation of Fluorine-Containing Polyethylsiloxane by Ring-Opening Polymerization of Cyclic Siloxanes Catalyzed by Phosphazene Base

    • The ring-opening copolymerization (ROP) of hexaethylcyclotrisiloxane (E3) and 1,3,5-trimethyl-1,3,5-tri(3,3,3-trifluoropropyl) cyclotrisiloxane (F3) was catalyzed by organic cyclotrisiloxane base (CTPB) under mild conditions. CTPB showed high catalytic activity for the polymerization of E3 and F3. Linear polydiethylsiloxanes (PDES) and poly(diethyl-ran-trifluoropropylmethyl) siloxanes (PDES-ran-PTFPMS) with different mole fractions of trifluoropropylmethyl siloxane group (F unit) (mole fraction (fF): 0−46%) were successfully synthesized. The composition and structure of the PDES-ran-PTFPMS copolysiloxanes were characterized in detail by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR), and the glass transition temperature (Tg) and crystallization behavior of the polymers were comprehensively analyzed by differential scanning calorimetry, and the water-oil contact angle of fluorine-containing polyethylsiloxane film was investigated by microscopic contact angle test. The chemical positions of the resonance peaks in the nuclear magnetic resonance spectrum (1H-NMR and 29Si-NMR) were analyzed, indicating that the PDES-ran-PTFPMS was successfully prepared. The results of differential scanning calorimeter (DSC) indicated that the crystallization of polydiethylsiloxane at low temperature can be entirely inhibited by the introduction of F unit. The obtained PDES-ran-PTFPMS has a low glass transition temperature Tg (−134 ℃), has very excellent low temperature performance, and is an ideal precursor material for low temperature resistant rubber materials. When fF is higher than 6.0%, the crystallization behavior was inhibited. The results of contact angle test of fluorine-containing polyethylsiloxane film demonstrated that the introduction of F unit into the PDES chain can effectively improve its hydrophobicity and decrease the oil wettability.
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