木素磺酸盐在纸浆纤维表面的层层自组装及其疏水改性功能

利用木素磺酸盐 (LS) 与Cu2+层层自组装的方式对纸浆纤维进行了表面修饰，并研究了表面润湿性的变化。X射线光电子能谱证明了纤维表面S和Cu的含量随着LS与Cu2+ 的交替组装而增加，这说明LS和Cu2+在纤维表面的层层自组装是可行的。原子力显微镜对纤维表面的研究表明，随着层层自组装的进行，纤维表面的微细纤维逐渐被木素致密覆盖；表面木素的增加致使相图的平均相位逐渐增大，说明了表面疏水性的提高。通过测定动态接触角发现，纤维的初始接触角随着自组装层数的增加而增大，且一定时间(0.08s)内接触角的下降速率在减小。当组装5层木素后，纤维表面的初始接触角由0°提高至104.8°，0.08s 后下降至78.9°，表面由高度亲水性变为具有一定疏水性。通过控制SL自组装的层数可以有效且可控地实现纸浆纤维的疏水改性。

Layer-by-layer Assembly of Lignosulfonates on Pulp Fiber Surface and Its Hydrophobic Modification Function

Layer-by-layer (LbL) self-assembly of Lignosulfonates (LS) and Cu2+ were applied to modify the surface of pulp fiber. The wetting properties were also studied. X-ray photoelectron spectroscopy results showed that the contents of sulfur and copper on fiber surface increased as the alternate assemblies of LS and copper ion proceeded, which indicated the successful LbL assembly of lignosulfonates on fiber surface. AFM results showed that microfibrils on fiber surface were gradually compactly covered by granular lignin particles with the process of LS self-assembly. The average phase of AFM phase images increased with the increased content of lignin, which suggested that hydrophobictiy of fiber surface, was improved. From the measurements of dynamic contact angle, it was found that the initial contact angle was increased as LS-Cu2+ multilayer grew, as well as the decrease rate of contact angle (slowed in 0.08s). The initial contact angle was increased from 0°to 104.8°after fiber surface was modified by 5-layer self-assembled multilayer, and then decreased to 78.9°after 0.08s. The results suggested the excessive hydrophilicity fiber surface was modified to have some degree of hydrophobicity. Therefore, hydrophobic modification of fiber surface can obtain by controlling assembled layer. The hydrophobictiy of fiber surface can be effectively improved in a controllable manner by constructing self-assembled multilayer of LS and Cu2+ on the surface.