【作者】 刘国宇；

【导师】 顾大明；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2013， 博士

【摘要】 综述了双子表面活性剂的特点及国内外相关研究领域的发展现状。以咪唑、不同链长的溴代烷等为主要原料，合成系列以亚甲基链为联接基团，具有对称和不同疏水基团链长及联接基团链长的系列对称型双子咪唑表面活性剂，采用红外、核磁谱图和元素分析的手段表征活性剂分子结构。在分析证实产物为目标结构的基础上，用表/界面张力法、电导率法测定了五种具有对称结构的系列对称型双子咪唑表面活性剂在溶液中的表界面活性、构效关系及胶束化热力学性质，结果显示，活性剂分子表现出良好的表面活性，当活性剂分子联接基团长度一定时，随分子两侧疏水烷基链碳原子数的增加，活性剂分子吸附于气/液界面的趋势逐渐增大，双子咪唑表面活性剂降低表面张力的效率也逐渐升高；当活性剂分子疏水烷基链长度不变时，系列双子咪唑表面活性剂中联接基团长度较短的具有较高的表面活性，更易吸附在气/液界面处。对于同一种结构的双子咪唑表面活性剂而言，在室温至45℃阶段，随着温度的升高，其胶束反离子结合度逐渐增大，胶束体尺寸逐渐增加；当温度升至45℃以上时，结合度呈现下降趋势，胶束体尺寸减小；吉布斯自由能变化情况说明，系列对称型双子咪唑表面活性剂在水溶液中胶束化为自发进行过程，其体系为热力学稳定体系；随温度的增加，自由能逐渐降低，胶束体稳定性逐渐提高；温度相同，当活性剂分子疏水基团碳原子数增加时，自由能逐渐降低，胶束稳定性上升；而随着亲水基团长度的增加，自由能逐渐增大，胶束体稳定性逐渐减弱。针对实验手段难以在分子层次上解释胶束化机理及构效关系的缺陷，设计了在微观水平上对多种不同结构表面活性剂性质进行研究的分子动力学系统，并通过压力张量、自由能微扰、回旋半径和径向分布函数等方法系统的研究了对称型双子咪唑表面活性剂、季铵盐型两性离子双子表面活性剂以及传统烷基芳基磺酸盐型表面活性剂的表面活性、热力学及动力学性质。分子动力学研究结果表明，压力张量、自由能微扰法等分子动力学手段研究三种不同结构表面活性剂的理论结果与实验值相近，说明所设计的分子动力学系统和模型可以用于预测多种表面活性剂溶液中的表面活性、热力学及动力学性质；对于结构确定的双子咪唑表面活性剂，其表面活性和在水溶液中的胶束化能力与温度、疏水基及联接基团的结构有关，随着温度的升高，分子热运动加剧，胶束化能力降低；联接基团长度不变时，随着疏水烷烃链碳原子数增加，胶束化能力得到提高；联接基团长度不同的离子液体型双子咪唑表面活性剂可能遵循不同的胶束化机理，联接基团长度小于6时，随着联接基团长度增加，分子胶束化能力降低；当联接基团长度大于6时,分子胶束化能力提高。在相同条件下，两性离子液体型双子表面活性剂体系胶束化自由能变高于双子咪唑表面活性剂，说明前者水溶液中形成的胶束体与后者相比稳定性较差；而当外界条件相同时，两性离子液体型双子表面活性剂与传统驱油用烷基芳基磺酸盐表面活性剂在溶液中胶束化过程的热力学性质相近。采用量子化学拓扑理论和多种动力学方法研究系列双子咪唑表面活性剂单分子性质、在溶液中的水合作用以及与水分子和其它表面活性剂间的复配效应。结果表明，不同理论计算方法中，量子化学拓扑法计算结果最为精确；表面活性剂分子疏水尾部受极性亲水基团的影响，带有少量弱电荷而略显部分极性；分子极性基团总电荷受到联接基团碳原子数的显著影响，且随原子数的增加而增大；随着亲水基团长度的增加，分子烷基尾链电荷显著增大。双子咪唑表面活性剂与水分子间可以通过氢键作用形成具有一定几何形状的团簇体，当水分子数在1~3之间时，活性剂分子极性基团主要与水分子以1:1氢键形成水合团簇体；当水分子数增加至4~5时，活性剂将与水分子分别以1:2和2:2氢键形成环形和笼型水合团簇体；对水合团簇体的结合能及自由能分析表明，理论计算所得到的水合团簇体为热力学稳定体系，且随着水分子数的增加，团簇体稳定性得到提高。双子咪唑表面活性剂与传统阴离子表面活性剂复配后的电子密度等高线图分析结果表明，分子烷基链尾部间带有部分电荷，在相互聚集时存在静电排斥力；当活性剂浓度较低时，其分子间静电排斥力较弱可以忽略；随着活性剂分子浓度继续增大，静电斥力影响将逐渐增加，不利于胶束体的形成；由于联接基团长度可以显著影响其疏水基尾链的电荷，因此，可以考虑改变联接基长度来调控或改善离子液体双子咪唑表面活性剂尾链间的静电排斥力，使之更加适应三次采油中不同驱油用表面活性剂间的复配应用。更多还原

【Abstract】 In this paper, the content, significance and development of synthesis and propertiesof Gemini surfactants in the relevance fields are summarized. A series of Geminiimidazolum surfactants with methylene spacer chains are synthesized by the reaction ofimidazolium, different bromoalkane and so on. The structure of the target product ischaracterized by1HNMR. The results show that all synthetic surfactants are objectiveconfigurations. The surface activities, structure-activity relationship and thermodynamicproperties of micellization of symmetric ionic-liquid Gemini imidazolum surfactants areinvestigated by means of surface tension and conductivity. The results show that theGemini imidazolum surfactant own high surface activities. As the carbon atoms ofhydrophobic group increase, the adsorption at the air-aqueous interface for Geminiimidazolum surfactant with fixed length of hydrophilic group is easier and the effciencyfor reducing the surface tension is increased; For the Gemini imidazolum surfactantwith shorter hydrophilic group, it has the higher surface activities and easier adsorptionat air-aqueous interface with the fixed hydrophobic group.At the low temperature, as the temperature increase, the counterion of micellizationincrease while the counterion decrease at higher temperature (45℃); The change ofGibbs free energy show that the micellization in aqueous solutions is a spontaneous andstable process; As the temperature increase, the free ernergy decrease but the stableproperties of micellization increase; At the same temperature, the free energy decreasewith increasing the length of hydrophobic group but increase with increasing the lengthof hydrophobic group.A molecular dynamics system suitable for many types of surfactant with differentstructure is constructed in this paper due to the drawback of exprimental investigatingon the micellization mechanism and structure-activity relationship from the molecularlevel. The surface activities, structure-activity relationship, thermodynamic anddynamics properties are investigated by means of pressurer tensor, free energyperturbation, radius of gyration and radial distribution function methods. The moleculardynamics results show that the theoretical value calculated from the moleculardynamics is close to the experimental value, and the system constructed can be used todiscriminate and predict the surface, thermodynamic and dynamics properties ofdifferent surfactants; For the surfactant with fixed structure, the surface activities andfavourability micellization are related to temperature, hydrophobic and hydrophilicgroup; As the temperature rises, the micellization of ionic liquid-type Geminiimidazolium surfactants becomes more difficult with the aggravation of molecularmovement; As the number carbon atom in the alkyl chains is increased, the tendencyand stability of micellization both increase; In addition, we found that ionic liquid-type Gemini imidazolium surfactants with different spacer lengths should follow the variousmechanism of micellization; If the length of spacer is less than6, as the carbon atoms ofspacer group increase, the formation ability of the micelles of surfactant is enhanced;But the formation ability of the micelles of surfactant decrease with the longer spacer(more than6).Under the same condition, the free energy of micellization of zwitterion Geminisurfactants are higher than the Gemini imidazolum surfactants, meaning that thestability of former are poor than the latter. Since the thermodynamic properties ofzwitterion Gemini surfactants are close to the traditional anion surfactant, it may showthe better compound properties than the ionic liquid Gemini imidazolum surfactants.The quantum chemical topology and molecular dynamics methods are applied tothe single molecular property, hydration in the aqueous solution and compound amongthe different surfactants. The results show that the hydrophobic tails of surfactant own anegative charge due to the influence of hydrophilic group; The total charge of polargroup can be greatly influenced by the numbers of carbon atoms of spacer group; As thelength of spacer group increase, the end part of hydrophobic group increase.Ionic liquid Gemini imidazolum surfactant can form the geometry cluster withwater molecules by constructing the hydrogen bonding formation; As the range ofmolecular from1to3, the hydrogen bonding formation between polar group ofsurfactant and water is1:1. As the number of water molecule is increased to4or5, thehydrogen bonding formations are2:1and2:2with the ring and cage hydration cluster;The analysis results for binding and free energy of hydration cluster show that thehydration cluster is a stable thermodynamic system; With the increased numbers ofwater molecular, the stability of cluster increase.The contour map with compounding ionic liquid Gemini imidazolum surfactantand traditional anionic surfactant shows that the the electrostatic repulsion force mayexist among the aggregation of hydrophobic groups due to the negative charge in theend of the alkyl chain; As the concentration of surfactant is low, the electrostaticrepulsion force can be ignored in the system; However, the influence of electrostaticrepulsion force should be important with increasing the concentration constantly andmay be unfavourable to form the micellization; Therefore, we can consider to changethe electrostatic repulsion force so that it can be suitable to the application of compoundamong different surfactants in the enhanced oil recovery by improving the length ofspacer group.更多还原