木质素磺酸用作导电高分子分散剂的基础问题研究

Preparation of water-dispersive conductive polymer complexes by using natural renewable resource-lignosulfonic acid as dispersant of conductive polymers not only opens up a new application area for high value-added utilaztion of lignin-based products, but also builds a new growing point for development of conductive polymer. In this project, water-dispersive poly(3,4-ethylenedioxythiophene) (PEDOT)/ lignosulfonic acid (LS) conductive complexes are first prepared by taking advantage of the adsorbing and dispersing properties of LS, and a strong interaction between LS and polycations, and then used as antistatic agents. However, microstructure of LS is complex, and the interaction mechanism between LS and PEDOT are not fully understood, which brings uncertainty in preparing PEDOT/LS dispersions. This problem can be solved by narrowing the parameters of the complex LS structure into molecular weight and sulfonation degree, by understanding the microstructure and its regulating mechanism of LS, by studying the static equilibrium, pi-pi and pi-cation interactions between LS and PEDOT, and by uncovering the anion doping and dispersing mechanisms. Through building relationships among the structural characteristics, physicochemical property, and applied performance of PEDOT/LS conductive complexes, this work can provide a theoretical basis for preparing lignin/conductive polymer complexes with high performance, and lead to developing interdisciplinary field of natural polymers and synthesized polymers.

将天然可再生资源-木质素磺酸(LS)用作导电高分子分散剂制备水分散性导电高分子复合物，既开辟木质素产品高附加值应用的一个新领域，同时为水溶性导电高分子发展找到了新的生长点。本项目首次以木质素磺酸(LS)为原料，利用LS的吸附与分散性能、与聚阳离子的强相互作用，得到水分散性聚（3,4-乙撑二氧噻吩）（PEDOT）/LS导电复合物。该复合物在导电高分子抗静电剂领域有广阔的应用前景。但LS的微结构复杂，且LS与PEDOT之间的作用机理不太清楚，导致PEDOT/LS导电复合物的制备具有盲目性。通过将LS结构特征简化成两个关键结构参数:分子量和磺化度，理解微结构及其调控机制，对LS与PEDOT之间的静电平衡、pi-pi、pi-阳离子等强相互作用做深入研究，揭示LS的阴离子掺杂机理和分散机理，为制备高性能的水分散性木质素/导电高分子复合物提供理论依据，并促进天然高分子和合成高分子交叉领域的科学发展。

水分散性聚（3,4-乙撑二氧噻吩）（PEDOT）/木质素磺酸（LS）导电复合物在导电高分子抗静电剂领域有广阔的应用前景。但LS的微结构复杂，且LS与PEDOT之间的作用机理不太清楚，导致PEDOT/LS导电复合物的制备具有盲目性。本项目首次通过Pickering乳液聚合法及化学氧化聚合法制备得到了高电导率的PEDOT/LS分散液，并对LS与PEDOT之间的静电平衡、pi-pi、pi-阳离子等强相互作用做深入研究，揭示了LS的阴离子掺杂机理和分散机理。主要结论如下：.以LS为分散剂和掺杂剂，以过硫酸铵为氧化剂，采用传统乳液聚合法制备了PEDOT/LS纳米颗粒；然后将该纳米颗粒作为固体稳定剂制备了Pickering乳液，通过Pickering乳液聚合法制备了新的导电复合物(PEDOT/LS-PEP)，大大提高了电导率。对PEDOT/LS和PEDOT/LS-PEP复合物进行结构表征，聚合后PEDOT/LS-PEP核内PEDOT总含量增大，载流子相应增多，核内的PEDOT链相互缠绕形成更大的网状结构，有利于载流子在PEDOT链间的传递，从而提高了复合物的电导率。并利用乙二醇(EG)处理提高了PEDOT/LS复合物的电导率，对EG处理前后的PEDOT/LS薄膜进行了结构和形貌表征，发现薄膜表面上不导电的LS含量减少，PEDOT富集，出现明显的相分离；同时，PEDOT链的共振结构从苯型结构转变成醌型结构，两者共同促进载流子在PEDOT链间的传递，从而提高了复合物的电导率。.将PEDOT单体分散在水溶性LS载体中，通过化学氧化聚合，得到了水分散性PEDOT/LS导电复合物，并分别配制酸性及中性抗静电剂应用于玻璃基材。涂层外观光滑平整透明，表面电阻小于108 Ω/sq，耐水洗且耐高温，附着力强，满足抗静电涂层的要求。PEDOT/LS的微结构为类似于核壳结构的聚电解质球体，其中等量电荷配比的PEDOT/LS复合物位于球体内部，而亲水性的聚阴离子LS包裹在球体表面。LS充当PEDOT的分散剂与掺杂剂，LS与PEDOT之间存在π-π作用与静电作用。碱能使PEDOT脱掺杂。加入碱后，PEDOT/LS分散液颜色从蓝色变成紫色，同时表面电阻值升高。向碱性PEDOT/LS分散液中加入酸，去掺杂态的PEDOT能够恢复掺杂态，重新导电。但对于碱性不同的PEDOT/LS，恢复掺杂态的程度也不相同。