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研究了酚羟基对木质素在固液界面上形成的吸附层致密程度的影响及作用机理.通过对碱木质素(AL)进行乙酰化处理制备了酚羟基含量显著减少的乙酰化木质素(ACAL).借助耗散型石英晶体微天平(QCM-D)研究了溶液环境中AL和ACAL所形成的单层吸附膜致密程度的差异,结合紫外-可见光光谱仪(UV)和原子力显微镜(AFM)研究了AL和ACAL分别与聚二烯丙基二甲基氯化铵(PDAC)交替自组装所形成的多层吸附膜的致密程度在干燥状态下的差异.结果都表明,酚羟基的存在会使木质素吸附层致密程度降低.分析认为,酚羟基的存在不利于木质素中的芳香环形成共面结构,酚羟基含量降低后会引起芳香环间的共面性增强,促进形成致密的π-π堆积,从而使得木质素吸附层致密程度增大.
The effect of phenolic hydroxyl on the densification degree of lignin formed on the solid-liquid interface was studied, and the mechanism of action was discussed. Acetylated lignin (ACAL) with significantly reduced phenolic hydroxyl content was prepared by acetylation of alkali lignin (AL) ). The difference of the density of monolayer adsorption films formed by AL and ACAL in solution environment was studied by means of dissipative quartz crystal microbalance (QCM-D). Combined with UV-Vis and atomic force microscopy (AFM) The difference in the degree of densification of multilayer adsorbed membranes formed by the alternating self-assembly of AL and ACAL with polydiallyldimethylammonium chloride (PDAC) in the dry state showed that the presence of phenolic hydroxyl groups The density of lignin adsorbed layer decreased.Analysis shows that the existence of phenolic hydroxyl group is not conducive to the formation of lignin aromatic ring formation of coplanar structure, reduced phenolic hydroxyl content will cause the aromatic ring between the coplanarity, and promote the formation of dense π- π stacking, making the density of lignin adsorption layer increases.