Smart Hydrophobic-Hydrophilic Self-Switching Cellulosic Materials Synthesized by Regioselective Functionalization

Meiyan Lin, Kunfeng Xia, Pengbo Lu, Yanghao Ou, Lingfeng Su, Detao Liu

Abstract


Smart hydrophobic-hydrophilic self-switching cellulosic materials were synthesized by regioselective functionalization of cellulose in green Ionic Liquids (ILs). The thermal analysis indicated that the introduction of a macromolecular structure including a trityl or heptafluorobutyric group onto the cellulose chain increased the thermal stability of the cellulose derivatives. Wetting contact angle of the surface decreased from 103° to 73° as the holding time increased at ambient conditions (19.8 °C, 65%). After wetting, the surface free energy increased from 11.03 to 34.09 J·m, of which the polarity component increased from 60.92% to 94.19%. The XPS analysis indicated that the content of oleophobic-hydrophobic CF3-CF2-CF2-CO- groups at the exposed surface decreased after wetting, while the hydrophilic HOOC- groups increased, which verified the self-switching process between the hydrophobic and hydrophilic properties within the cellulosic materials. The self-switching characteristic means that the biodegradable cellulosic materials have suitable selectivities for high-impact applications in various fields.

Keywords


Self-switchable process; Ionic liquids; Cellulose; Trityl group; Hydrophobic-hydrophilic process

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