【作者】 李辉；

【导师】 付时雨；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2012， 博士

【摘要】 工业木素作为造纸工业的副产品，具有价格低廉、产量丰富的特点，然而大部分被用于焚烧获取能量，仅有少部分从制浆废液中分离出来用于制备高附加值精细化工产品。本论文以工业木素为主要材料，基于工业木素与金属离子的配位作用及工业木素与带正电荷物质的静电相互作用，采用层层自组装的方法，在合适的固体基底表面构筑自组装多层膜，追踪了自组装多层膜的增长方式，表征了自组装多层膜的表面形貌，并考察了自组装多层膜对固体基底表面的功能化修饰作用，为工业木素资源高值化利用提供了一条新的途径。基于木素磺酸盐（LS）与金属离子(Cu²⁺)的配位作用，采用层层自组装的方法分别在石英片和纤维表面构筑了LS/Cu²⁺自组装多层膜，并对LS/Cu²⁺多层膜的增长方式、表面元素组成及形貌特性进行了分析，同时考察了LS/Cu²⁺多层膜对纤维润湿性能及纤维手抄片强度性能的影响。结果表明，LS和Cu²⁺的配位层层自组装是可行的，LS/Cu²⁺多层膜在石英和纤维表面的增长是均匀的、连续的；LS/Cu²⁺多层膜的特征元素（S元素和Cu元素）的含量均随着LS层数的增加而增加，纤维表面LS含量与LS层数呈现良好的线性关系，表明每一层吸附的LS量是相等的；AFM相图表明随着层层自组装的的进行，纤维表面的微细纤维逐渐被颗粒状的LS所覆盖，且相图中的平均相位也在逐渐增大；动态接触角的测定结果表明LS/Cu²⁺多层膜可以有效改善纤维表面的疏水性，随着LS层数的增大，纤维的初始水接触角在增大，接触角的下降率在减小，当组装了五层LS后，纤维的初始水接触角由0°提高至115.5°，0.12s后下降至97.9°，可见，通过控制LS层数，可以有效且可控地实现纤维表面的疏水改性；然而在纤维表面构筑LS/Cu²⁺多层膜会对纤维手抄片的强度性能产生负面影响。为了改善纤维手抄片的强度性能，采用阳离子聚丙烯酰胺（CPAM）和LS静电层层自组装的策略，分别在石英片和纤维表面构筑CPAM/LS多层膜。结果表明，CPAM和LS的静电层层自组装是可行的，CPAM/LS多层膜在石英和纤维表面的增长是均匀的、连续的；纤维表面的Zeta电位随着自组装的进行呈现有规律的反转；CPAM/LS多层膜的特征元素（S元素和N元素）的含量随着组装双层数的增加而增加，纤维表面LS含量与组装双层数呈现良好的线性关系，表明每个双层中吸附的LS量是相等的；随着CPAM/LS多层膜在纤维表面的增长，纤维表面的微细纤维逐渐被颗粒状的LS所覆盖，且纤维表面RMS粗糙度也逐渐增大；CPAM/LS多层膜可有效改善纤维表面的疏水性，表现为随着组装双层数的增加，纤维表面的初始接触角逐渐增加，接触角的下降率逐渐减小。当纤维表面组装了（CPAM/LS）5多层膜时，其初始水接触角可达109.2°，1.0s后下降至90.7°，表面仍具有一定的疏水性；同时CPAM/LS多层膜还可以有效地改善纤维手抄片的强度性能和印刷适性。通过Mannich反应向LS分子上引入了脂肪族长碳链，并将改性后的木素磺酸盐（MLS）应用于静电层层自组装体系，在纤维表面构筑CPAM/MLS多层膜对其进行疏水改性。另外，对CPAM/MLS自组装体系进行改进，以期获得疏水性能稳定的疏水表面。结果表明，LS、甲醛和十二胺的Mannich反应最优条件为：反应温度90℃，反应时间6h，n（LS）: n（十二胺）: n（甲醛）=1:1:1.3；CPAM/MLS多层膜的特征元素（S元素）含量随着组装双层数的增加而增加，纤维表面的Zeta电位随着自组装的进行而呈现有规律的反转；在组装层数相同时，CPAM/MLS多层膜改性的纤维表面RMS粗糙度均比CPAM/LS多层膜改性的纤维表面RMS粗糙度大；动态接触角的测试结果表明CPAM/MLS多层膜对纤维的疏水改性效果较CPAM/LS多层膜有所提高，且对纤维手抄片的强度性能影响不大。利用十三氟辛基三甲氧基硅烷（FAS）对CPAM/MLS多层膜改性后的纤维手抄片进行修饰，可制备超疏水表面，且疏水性能稳定性较好，（CPAM/MLS）5/FAS修饰的纤维手抄片，其初始水接触角可达159.7°。利用二氧化钛（TiO₂）纳米颗粒与LS静电层层自组装的方法在石英片表面构筑具有光催化能力的TiO₂/LS多层膜，并评价了TiO₂/LS多层膜的光催化能力。结果表明，TiO₂/LS多层膜在石英片表面均匀的、连续的增长，其平均高度、表面RMS粗糙度随着多层膜层数的增加而增加；在相同的紫外照射时间下，TiO₂/LS多层膜对甲基橙的降解效率与TiO₂的层数呈良好的线性关系；在多层膜最外层物质相同时，TiO₂/LS多层膜对大肠杆菌的分解程度随着组装层数的增加而增大，且TiO₂处于多层膜最外层时对大肠杆菌的分解效果较佳。采用静电层层自组装的方法在纸浆纤维表面构筑阳离子淀粉（CS）/碱木素（AL）多层膜用于制备抗氧化纸，测定了CS/AL多层膜改性后纸浆纤维的抗氧化性能。结果表明，CS/AL多层膜在纤维表面是连续、均匀的增长的；随着自组装的进行，纤维表面逐渐被尺寸为28nm30nm的AL颗粒所覆盖；CS/AL多层膜改性后的纸浆纤维在经过自由基氧化处理后，能较好地保留纤维素的聚合度和纤维的强度，能力与漂白CTMP相当，而且CS/AL多层膜改性纸浆的白度稳定性较漂白CTMP要好。更多还原

【Abstract】 Technical lignin is a low-cost and abundant by-product of pulp and paper industry, amajor part of technical lignin is incinerated as a fuel for the production of energy, only1-2%of technical lignin is isolated from spent pulp liquors and employed in a wide range of finechemical products. In this paper, self-assembled multilayers were built up on proper solidsubstrate surface by using layer-by-layer （LBL） self-assembly technique based oncoordination interaction between technical lignin and metal ions or electrostatic interactionbetween technical lignin and positively charged substance. The growth modes ofself-assembled multilayers were monitored, the morphologies of self-assembled multilayerswere characterized, and the surface functionalization of solid substrates with self-assembledmultilayers was considered. This paper proposed a new way for the high-value use oftechnical lignin.Self-assembled multilayers of lignosulfonates （LS） and Cu²⁺were built up on both quartzslide and cellulose fiber surface by using LBL self-assembly technique based on coordinationinteraction between LS and Cu²⁺. The growth mode, surface chemical composition andmorphology of LS/Cu²⁺multilayers were analyzed, the effects of LS/Cu²⁺multilayers onfibers wetting properties and handsheet strength were investigated. The results showed thatLBL self-assembly of LS and Cu²⁺was feasible, stepwise LS/Cu²⁺multilayers growth wasoccurred and this deposition process was highly reproducible. The contents of characteristicelements （i.e. S and Cu） of LS/Cu²⁺multilayers increased with the number of LS layers,furthermore, the calculated surface LS content increased linearly as a function of LS layers,indicating that equal amount of LS was absorbed on each layer. The AFM phase imagesshowed that the cellulose microfibrils on fiber surface were gradually covered by LS particlesas self-assembly proceeded, resulting in the increase in average phase of AFM phase images.The dynamic contact angle results showed that the hydrophobicity of cellulose fiber waseffectively improved by constructing LS/Cu²⁺multilayers on fiber surface. The initial watercontact angle gradually increased and the attenuation rate of the water contact angle graduallydecreased with the number of LS layers. The initial water contact angle increased from0°to115.5°as the cellulose fiber was modified with a5-layer LS multilayer, and then decreased to97.9°after0.12s, suggesting that the controllable hydrophobicity of cellulose fiber can beachieved depending on the number of LS layers. However, it is unfortunate that LS/Cu²⁺multilayers have negative effect on strength property of handsheet.To improve the strength property of handsheet, multilayers composed of cationic polyacrylamide （CPAM） and LS were built up on both cellulose fiber surface and quartz slideusing electrostatic LBL self-assembly technique. The results showed that the electrostaticLBL self-assembly of CPAM and LS was feasible, the growth of CPAM/LS multilayers onboth quartz slide and cellulose fiber surface was uniform and successive. The Zeta potential offiber surface inversed after deposition of each layer, the contents of characteristic elements（i.e. S and N） of CPAM/LS multilayers increased with increasing bilayer number, and a goodlinear relationship was observed between the calculated surface LS content and the number ofbilayers. AFM phase images indicated that the cellulose microfibrils on fiber surface weregradually covered by LS granules as the multilayers grew, resulting in an increase in fibersurface roughness. The hydrophobicity of cellulose fiber was markedly increased throughfabricating CPAM/LS multilayers on fiber surface. More specifically, the initial contact angleincreased gradually with the number of bilayers. When a （CPAM/LS）5multilayer was formedon the fiber surface, the initial water contact angle reached to109.2°, suggesting that thisself-assembly strategy can lead to the formation of a hydrophobic surface on cellulose fiber.On the other hand, the attenuation rate of contact angle decreased with the number of bilayers,the initial contact angle changed from109.2°to90.7°after1.0s when the cellulose fibermodified with a （CPAM/LS）5multilayer. Moreover, the strength property and printability ofhandsheet were effectively improved by constructing CPAM/LS multilayers on cellulose fibersurface.Long aliphatic carbon chain was introduced to LS macromolecule through Mannichreaction. The modified LS （MLS） was applied to electrostatic LBL self-assembly system, andthe CPAM/MLS multilayers were built up for hydrophobicity modification of cellulose fibersurface. Moreover, LBL self-assembly system of CPAM and MLS was improved to obtain astable hydrophobic surface. The results indicated that the optimal Mannich reactionconditions were as follows: reaction temperature90oC, reaction time6h, n（LS）:n（dodecylamine）: n（formaldehyde）=1:1:1.3. The content of characteristic element （S） of theCPAM/MLS multilayers increased, and the Zeta potential of fiber surface inversed regularlyas the LBL self-assembly proceeded. The RMS roughness of fiber surface modified withCPAM/MLS multilayers was higher than that of fiber surface modified with CPAM/LSmultilayers when the number of bilayers was same. The hydrophobicity of fiber surfacemodified with CPAM/MLS multilayers was improved more significantly than that of fibersurface modified with CPAM/LS multilayers. Moreover, The CPAM/MLS multilayers haveno negative effect on the strength property of handsheet. The handsheet prepared from a（CPAM/MLS）5multilayer modified fibers was further coated with trimethoxytridecafluorooct -ylsilane, and a stable superhydrophobic surface having an initial contact angle of159.7°wasobtained.Photocatalytic multilayers composed of anatase TiO₂nanoparticles and LS werefabricated on quartz slides by the LBL self-assembly technique, and the photocatalyticproperties of TiO₂/LS multilayers were evaluated. The results showed that stepwise multilayergrowth occurred on the substrate and this deposition process is highly reproducible. AFMmorphological images showed that quartz slide was fully covered by particles and the averagethickness, the surface RMS roughness of the TiO₂/LS multilayers gradually increased as theLBL self-assembly proceeded. The increase in decomposition efficiency of methyl orangeunder the same UV irradiation time was linear with the number of TiO₂layers. The degree ofdecomposition of bacterial increased with the increasing number of bilayers when the samesubstance was in the outermost layer, and bacterial decomposition ability of the samples withTiO₂in the outermost layer was better than that of the samples with LS in the outermost layer.To prepare antioxidative paper, the multilayers consisted of cationic starch （CS） andalkali lignin （AL） were constructed on the pulp fiber surface using electrostatic LBLself-assembly technique, the antioxidant abilities of the pulp fibers modified with CS/ALmultilayers were investigated. The results indicated that the growth of CS/AL multilayers onpulp fibers was successive and uniform. The fiber surface was gradually covered by ALgranules with diameter of28nm30nm as the number of bilayer increased. For the pulpfibers modified with CS/AL multilayers, there was no obvious change in cellulose degree ofpolymerization and fiber strength after radical oxidation treatment. The modified pulp andbleached CTMP are equally matched in inhibition oxidative degradation of cellulose.However, the pulp modified with CS/AL multilayers has higher stability of brightness thanbleached CTMP pulp.更多还原