【作者】 赵玉荣；

【导师】 陈晓；

【作者基本信息】 山东大学 ， 胶体与界面化学， 2011， 博士

【摘要】 表面活性剂在不同溶剂中能够参与构建各种类型的有序聚集体,包括胶束、液晶、囊泡、微乳液、凝胶和固态有序聚集体等。以往的工作中,人们对典型表面活性剂在不同溶剂中的聚集行为进行了深入透彻地研究。伴随着表面活性剂工业的发展,人们将“表面活性”一词逐渐引入新的领域,以其来定义一些非典型性的表面活性剂,进而研究它们参与构建的各类有序聚集体。非典型性表面活性剂多种多样,既包括含有相对疏水和相对亲水嵌段的两亲性三嵌段共聚物,也包括不同类型的长链离子液体,还包括其它一些符合表面活性剂定义的表面活性物质。为了更加透彻地了解这类特殊的物质,以拓展表面活性剂聚集体的种类并深入了解聚集体形成的微观动力学过程,本论文中,利用实验手段结合分子动力学模拟方法研究了这类物质,即非典型性表面活性剂参与构建的不同类型的有序聚集体,包括胶束、液晶、高水含量的凝胶和固态有机材料。论文的主要研究内容包括以下四个部分：1.非典型表面活性剂一长链咪唑盐类化合物构建有序聚集体的研究。包括两个方面：[C16mim]Cl在EAN和[Omim]PF6两类离子液体中聚集行为的研究,并与其在水中的聚集行为进行对比,分析了溶剂对聚集行为的影响；[C16mim]Cl与SDS和水三元体系构建凝胶的研究。结果表明：(1) [C16mim]Cl-EAN、[C16mim]Cl-[Omim] PF6和[C16mim]Cl-H2O体系中都有胶束相、六角相、层状相和反双连续立方相液晶形成。[C16mim]Cl在三种不同溶剂中形成液晶的初始温度按H2O、EAN和[Omim]PF6顺序逐渐升高且对应液晶区域逐渐变小。这说明,[C16mim]Cl在不同溶剂中的自组装能力是不同的,随溶剂Gordon参数的减小而减弱。同时,利用耗散颗粒动力学(DPD)模拟方法对[C16mim]Cl-EAN二元体系的室温相行为进行了模拟,对聚集体形成的微观动力学过程有了深入地了解。此部分研究对于更好地认识EAN和[Omim]PF6两类离子液体与水溶剂的不同以及[C16mim]Cl与传统表面活性剂的不同具有重要的意义。(2) [C16mim]Cl、SDS和水三元体系在水含量很高时即能形成凝胶。流变学和偏光显微镜测量手段均表明体系形成了具有较弱有序结构凝胶相,其流变学性质与传统体系形成的囊泡相类似；利用差示扫描量热手段对凝胶的热性质进行了研究,确定了其sol-gel转化温度；对比试验和分子动力学模拟结果表明：SDS/[C16mim]Cl/H2O体系中形成的阴阳离子复合物较其它对比体系有所不同,正是这种不同导致了凝胶相的形成；不同链长体系的对比试验表明,疏溶剂作用对凝胶的形成也起着至关重要的作用。本文研究的三元体系与传统阳离子表面活性剂参与构建的复配体系有很大不同,它打破了传统复配体系的一般规律,将有助于人们更好地认识长链咪唑盐这类特殊的非典型表面活性剂。2.非典型表面活性剂--长链哌啶盐类化合物构建有序聚集体的研究。包括两个方面：利用表面张力法、电导率法和荧光法研究了不同链长的长链哌啶盐类化合物CnPDB (n=12,14,16)在水中的胶束化聚集行为,并将其与长链咪唑盐(CnmimBr)、长链吡咯烷类化合物(CnMPB)和长链烷基三甲基溴化铵(CnTAB)在水中的胶束化聚集行为进行了详细比较；不同链长的CnPDB在水中构建溶致液晶的研究,详细考察了温度和浓度对结构参数的影响。结果表明：(1) CnPDB的临界胶束浓度随其链长的增加而减小。依据电导率数据计算了CnPDB胶束形成的各种热力学参数(ΔGm0,ΔHm0和ΔSm0),结果表明：CnPDB胶束的形成过程在低温下是熵驱动的,而高温下是焓驱动的。同时,将CnPDB的cmc值与CnmimBr、CnMPB和CnTAB的数据进行了比较。结果表明：当链长相同时,CnPDB的cmc略大于CnmimBr,而小于CnTAB和CnMPB。这主要是由于,CnPDB分子头基中存在六元环结构,较CnTAB和CnMPB具有更长的链长,能够更好地降低表面张力；尽管CnPDB的六元环比CnmimBr的五元环碳链更长,但后者含有的共轭双键大大增加了分子间的相互作用,因此能够更好地降低表面张力。这一研究使长链哌啶盐在水中的胶束化行为以及它与其它类型长链离子液体在水中胶束化聚集行为的共性和特性得到了更深地认识。(2)对于不同链长的CnPDB-水体系,在所研究的温度范围内,C12PDB-H2O只能形成六角相区域,其动态模量的变化符合Maxwell模型；而C14PDB-H2O和C16PDB-H2O则形成了六角相和反双连续立方相两个区域,此时六角相的流变学曲线都与弹性的gel-like体系的谱图一致,这与传统阳离子表面活性剂体系的性质是不同的。本节所研究的流变学性质随链长的变化情况可以拓展到其它类型的表面活性离子液体体系。同时,考察了液晶的结构参数和流变学参数随温度和浓度的变化情况,可以看到：随着温度和浓度的升高,表面活性剂分子排列更加紧密。这一研究加深了对长链哌啶盐在水中构建的溶致液晶的认识,对有关表面活性离子液体的工作是强有力的补充。3.非典型表面活性剂双亲嵌段共聚物在水中构建有序聚集体的理论模拟研究。利用介观动力学模拟方法,MesoDyn,分别研究了三嵌段共聚物EO20PO70EO20 (P123)在水中的聚集行为,并将模拟结果与实验结果进行了详细比较；还研究了三嵌段共聚物EO27PO61EO27 (P104)在水中的聚集行为,考察了EO嵌段的电荷大小对聚集行为的影响。结果表明：(1)随着P123含量的增加,体系逐渐形成了胶束、六角相和层状相,这与实验结果基本一致,证明了模拟结果的可靠性与准确性。而模拟结果与实验结果也存在或多或少的差异,特别在聚合物浓度较高时。这主要是由于,实验中对P123-水二元体系的混匀需要外力,这恰好对应分子模拟中的剪切应力。在实验中,混匀不同浓度样品所用的外力大小存在一定差别；而分子模拟中,在一定的浓度区域,所采用的剪切应力大小一致,因此导致模拟相图与实验相图的微小差别；通过有序度参数随模拟步数的变化可以考察不同浓度和PO含量体系相分离过程的快慢,它能更直观地展示聚集体形成的微观动力学过程。介观动力学模拟方法能够模拟介观尺度的聚集体并可给出聚集体形成的微观动力学过程,对实验是强有力的补充。(2)当P104浓度较高时,体系能够形成六角相和层状相。随着EO嵌段电荷的增加,所形成的六角相结构更加有序；而层状相的变化过程则有所不同：首先变得有序,随后转变成反六角相,最后又变得无序,这主要是由短程和静电相互作用导致聚合物链的卷曲程度不同引起的。此工作对实验有预测作用,对以往有关P104相行为的研究是很好的补充。4.非典型表面活性物质双亲染料分子构建固态有序聚集体的研究利用简易的离子自组装方式,将双尾链阴离子表面活性剂AOT与反电荷功能性染料分子罗丹明B(RB)进行自组装得到固态有序聚集体。考察了不同实验条件,比如温度、浓度、混合体系的放置时间等对产物形貌的影响。通过一系列条件尝试,得到了规则产物----星型产物的最佳形成条件。通过不同的实验手段对形成的固态有序聚集体进行了表征,结果表明,体系形成了AOT和RB摩尔分数比为1：1的星型产物。该产物中间是一个内核,边缘是由片状结构堆积而成的；稳态荧光和激光共聚焦显微镜实验表明：星型产物具有很好的荧光性,在特定领域存在潜在的应用价值。同时,还对星型产物形成的机理进行了初步探讨。更多还原

【Abstract】 The surfactants can be assembled into various aggregates in different solvents, including micelle, liquid crystal, vesicle, gel, and also the ordered aggregates in solid state. In the past years, the aggregation behaviors of traditional surfactants in different solvents were investigated in details. With the development of surfactant industry, the word surfactivity is involved in many other fields to define some untraditional surfactants and then people begin to investigate the aggregates formed from them. Getting more information on these non-classical surfactants can expand the aggregates species and also help us better understand the process of microphase separation. So the aggregates, including micelle, liquid crystal, vesicle, gel, and also the ordered aggregates in solid state, formed by several non-classical surfactants are investigated by both experimental and theoretical simulation methods in this dissertation. The studies can be divided into four parts.1. Investigations on the aggregates formed by long chained imidazolium salts. The work can be divided into two parts:investigations on the aggregation behavior of [C16mim]Cl in two different ionic liquids, EAN and [Omim]PF6, and then compared with that in water in order to make clear the solvent effect; Investigations on the gel phase formed in [C16mim]Cl/SDS/H2O ternary system. Following results can be obtained.(1) [C16mim]Cl can be assembled into micelle, hexagonal, and reverse bicontinous cubic phases in EAN, [Omim]PF6, and water. The threshold temperature of liquid crystalline (LC) phase formation increases in the order of water, EAN, and [Omim]PF6 but the areas of the LC phases display an opposite trend. This could be attributed to the different assembling abilities of [C16mim]Cl in these three solvents, which are quite related to their Gordon parameters. Meanwhile, the dissipative particle dynamics (DPD) method was used to simulate the phase behavior of [C16mim]Cl-EAN binary system at room temperature. Obtained results can give us microphase separation information which is much difficult to get by experimental methods. Such an investigation is quite important, which can help us better understand both similarities and differences among EAN, [Omim]PF6, and water or between [C16mim]Cl and traditional surfactants.(2) The ternary system SDS/[C16mim]Cl/H2O can form a novel gel phase at quite high water content. Results from rheology and POM measurements show that, the gel phase formed in the present system may be less ordered and has analogous rheological properties to that of vesicles formed in traditional systems. The sol-gel temperature can be ascertained by DSC technique. Control experiments and simulated results have certified that the complex formed by the [C16mim]Cl and SDS is dissimilar to that formed by the parallel catanionic surfactants with different head groups. Besides, the solvophobic interaction is also proved to play very important role in the gel phase formation. The phase behavior of this ternary system is quite different from those of previous ones, which had broken up the conventional phase behavior of catanionic systems and can help us better understand the special structure of the surface-active surfactant [Cnmim]Cl.2. Investigations on the aggregates formed by long chained piperidine salts CnPDB (n=12,14,16). The work can be divided into two parts:the micellization behavior of CnPDB in water were investigated by surface tension, conductivity, and fluorescence methods and then compared with that of long chained imidazolium, pyrrolidine, and traditional cationic surfactants; Investigations on the LLC phases formed by long chained piperidine salts CnPDB in water, both concentration and temperature effects were discussed in details. The following are obtained results.(1)The critical micelle concentration (cmc) value of CnPDB decreases with increasing alkyl chain length. Various thermodynamical parameters (ΔGm0,ΔHm0和ΔSm0) during the micelle formation process are calculated. The obtained results show that, the micelle formation process is entropy dominatant at low temperature while it is enthalpy dominated at high temperature. Meanwhile, the cmc value of CnPDB was compared with those of CnmimBr, CnTAB, and CnMPB. Obtained results show that, the cmc value of CnPDB is a little higher than CnmimBr but lower than CnTAB and CnMPB, which can be attributed to the following reasons:the alkyl chain length of CnPDB head group is longer than CnTAB and CnMPB, which is better for surface tension decrease; Even though the alkyl chain length of CnPDB head group is longer than CnmimBr, the conjugated bands in the later can increase the interactions between different molecules, which will result in lower cmc. Such an investigation can help us better understand the micellization behavior of CnPDB in water and also makes it clear for both the similarities and differences among various long chain ILs.(2) Through comparison of these three LC systems, it can be found that, for C12PDB/H2O system, only the H1 phase is observed and a Maxwell behavior is exhibited. However, both H1 and V2 can be identified in C14PDB/H2O and C16PDB/H2O systems and the H1 phase here shows a gel-like behavior, unlike the traditional cationic surfactants. Such different rheological properties for H1 phases in these systems inspire us to extend investigations to systems with other series of surfactive ionic liquids. Meanwhile, the structural and rheological parameters have been claculated. Obtained results show that, the surfactant molecules tend to arrange themselves more tightly with increasing temperature and concentration. Such investigations were a great supplement to previous reports on surfactive ionic liquid and can help us to better understand the LLC phases formed by the piperidine salts.3. Theoretical investigations on the aggregates formed by Pluronic polymers in water. The phase behaviors of Pluronic P123 or P104 in water were simulated by a mesoscopic method, MesoDyn and then compared with the experimental results in details; The effect of EO charge on the aggregation behavior was also explored. The following are obtained results.(1)With P123 concentration increasing, different aggregates including micelle, hexagonal and lamellar phases, are formed in P123-H2O binary system, which can reproduce most experimental phase regions and has proved the accuracy and responsibility of simulation results. The simulated phase ranges are more or less different from those established from experiment, especially at high polymer concentrations. This can be attributed to different phase mapping situations, i.e. the constant shear used in simulation vs. the varied external forces in experiment. The influences of PO block amount or P123 concentration on aggregate formation rate can be explored by the changing trend of order parameters with increasing time steps, which can present us the microphase separation information more directly. The mesoscopic simulation method is a valuable tool for the description of mesoscale morphology and can give us insight into the aggregates formation process, which will be a great supplement to the experimental results.(2) With the increase of P104 concentration, two different aggregates, hexagonal and lamellar phases, can be formed in aqueous solutions. The hexagonal phase becomes more and more ordered with the increase of charge per EO bead while lamellar phases display a quite different trend. With the increase of charge per EO bead, the lamellar phases first become more ordered, then it turns to be a reverse hexagonal phase and finally the structures become disordered. Such results can be attributed to the changing curvature of polymeric domains caused by both short range and electrostatic interactions. This simulation can help us predict the results of new series surfactants and is also a great supplement to previous investigations on the phase behavior of P104.4. A much facile ionic self-assembly (ISA) route was employed, through the complexation between a double-tailed anionic surfactant, aerosol AOT and a functional dye molecular Rhodamine B (RB), to fabricate the ordered aggregates in solid state. The effect of different experimental conditions, such as temperature, concentration, and the storage period were investigated. The optimum formation condition of the ordered aggregates, star-shape aggregate is obtained. Their properties and structures are characterized by different techniques. Obtained results show that, the stoichiometry between AOT and RB in the complexes is determined as a 1:1 molar ratio; The center of the complex is occupied by a circle dot while the surrounding is encircled by many sheets; The results from steady-state fluorescence and laser confocal microsopy indicate that, the formed complex is of great fluorescent properties and may have potential applications in some specific fields. A possible formation mechanism for the complex is also proposed.Thanks for the financial supports from the National Natural Science Foundation of China (No.20573066,20773080 and 20973104).更多还原