QAPVA/PMPVA复合物膜对95%乙醇脱水的IR研究

季铵化聚乙烯醇(QAPVA)与磷酸单酯化聚乙烯醇(PMPVA)自组装成聚离子复合物(PIC)膜。PIC膜用95%乙醇中浸泡48 h, 在20～120 ℃(间隔20 ℃)下测定吸水后PIC膜的IR，分析了>3 000 cm-1OH伸缩振动基频(ν_OH)随温度变化情况，探讨了水与膜中OH的氢键作用。由于ν_OH在3 000 cm-1以上重叠严重，结合1 300～1 700 cm-1水与PIC膜中离子键的静电作用，采用二维相关分析提高分辨率，定性描述了95%乙醇中水与PIC膜之间的结合方式。结果表明：>3 000 cm-1νOH的重叠谱带得到了分辨, 证明了水与膜内OH缔合优先吸附渗透，随温度变化早于膜内的OH自缔合被解吸与乙醇分离；确认了水和PIC膜内聚电解质基团的吸收, 证明了水与聚电解质基团靠静电作用被吸附, 随温度升高被解吸与乙醇分离。文章为PIC膜用于有机物脱水研究提供了一种简便高效的方法。

Infrared Spectral Studies of Separation of QAPVA/PMPVA Complex Membrane for Dehydrating Water of 95% Ethanol

Quaternized polyvinyl alcohol (QAPVA) and phosphate monoester polyvinyl alcohol (PMPVA) were self-assembled into polyion complex (PIC) membrane. The infrared spectra (IR) of PIC membrane dipped in 95% ethanol for 48 h were studied in the temperature range of 20-120 ℃ with an interval of 20 ℃ by analyzing the temperature dependent variations of OH stretch vibration base bands (ν_OH) at ＞3 000 cm-1. Hydrogen-bond of water in 95% ethanol with PIC was studied. Since the ν_OH strongly overlapped at ＞3 000 cm-1, combined with the static electric effect between water in 95% ethanol and ion-bond of PIC at 1 300-1 700 cm-1, two-dimensional infrared (2DIR) correlation analysis was applied to describe the possible combined modes between PIC and water in water-alcohol. The result shows that the ν_OH overlapped was distinguished at ＞3 000 cm-1, the change of water with varing tempertature was earlier than the intra-membrane OH self association and water was desorbed to separate from ethanol. The absorption peak of water and poly-electrolyte group intra-PIC membrane was identified. The water combined with ion-bond in PIC membrane by static electric effect was adsorbed with the temperature going up and separate from ethanol. The present study provides a simple method for investigating the separation performance of PIC membrane used in dehydration of organic compounds.