【作者】 罗钰；

【导师】 张现仁；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2010， 硕士

【摘要】 表面活性剂是一类有着固定的亲水亲油基团,并在溶液的表面或界面上定向排列,从而使溶液的表面张力显著下降的物质。20世纪30年代,以石油化工原料衍生物为主的表面活性剂和洗涤剂开始逐渐形成一门工业。经过几十年的发展,世界合成表面活性剂总量约为11000kt,有着“工业味精”的称号。因为表面活性剂具有润湿、抗粘、乳化、破乳、起泡、消泡以及增溶、分散、洗涤、防腐、抗静电等一系列物理化学作用,因此,它成为一类品种多样化、用途广泛的精细化工产品。如今,表面活性剂被广泛应用于洗涤剂、皮革、造纸、塑料、选矿、食品化工、采油、建筑、化妆品、农药等领域,也是许多工业部门必需的化学助剂。目前合成的表面活性剂种类有6000多种,而它们在人们日常生活中的应用领域也随着科技的不断进步而不断扩大,表面活性剂在其广泛应用中或多或少的起着决定性的作用。目前,表面活性剂的聚合反应是生物产品和大部分功能材料配制的重要方法。所以,对表面活性剂分子自组装行为和聚集形貌的研究已经成为当前全球研究的热点之一。本文利用了晶格蒙特卡洛(Lattice Monte Carlo, LMC)模拟方法来研究表面活性剂分子在限制性空间以及固液界面上的聚集性质,并针对聚集过程进行了讨论。从介观尺度上解释了表面活性剂分子在界面上的聚集行为,为理论研究和实际应用提供了重要依据。论文的主要工作内容如下：1.利用LMC模拟方法研究了表面活性剂在限制性球形空间内的聚集形貌和相的转化过程,重点研究了表面活性剂的头基和尾基之间、表面活性剂尾基和水之间的相互作用对表面活性剂聚集产生的影响,并给出了表面活性剂随着这些参数的变化而出现的聚集形貌,作了一定的解释说明。模拟结果发现,随着表面活性剂头基-尾基相互作用变化,表面活性剂在限制性球形空间内的聚集呈现三种不同构型：不规则的Y型网状结构、过渡结构和规则的螺旋结构；而在不同的表面活性剂尾基-水之间相互作用时,表面活性剂在限制性空间内的聚集呈现两种不同结构：不规则的Y型网状结构和规则的螺旋结构。并且这些结构的存在受到限制性球形半径大小、表面活性剂头基-尾基和表面活性剂尾基-水之间相互作用的影响。2.利用LMC模拟方法研究了曲率影响下表面活性剂在亲水固液界面上的聚集形貌过程,重点研究了表面活性剂在平板纳米材料和圆柱形纳米材料上的吸附行为。研究发现,H3T4表面活性剂在平板上的吸附形貌为蠕虫状结构,而在圆柱形纳米材料固体表面上的吸附呈现以下变化：当圆柱半径R=5和13时,表面活性剂在其上的吸附形貌为规则直线链状胶束,而当R=7,9,11时,表面活性剂在其上的吸附形貌为不规则的网状结构。表面活性剂在固体亲水表面上的聚集不仅受曲率(固体半径大小)的影响,还受表面活性剂分子自身构型和胶束大小的影响。更多还原

【Abstract】 Surfactants are a kind of substances which have both hydrophilic groups and hydrophobic groups. Surfactants can apparently lower the surface tension/the interfacial tension of the liquid/interface, and also make themselves orientation on the surface/interface.In this thesis, a model called lattice Monte Carlo (Lattice Monte Carlo, LMC) simulation method was used to study the behaviors of surfactants in the confined space and at solid-liquid interface with high curvature. We would like to explain the behaviors of surfactant aggregation at the interface of mesoscopic scale which play an important rule in the theoretical studies and practical applications. The main conclusions are as follows:1. Lattice MC Simulation was used to study the morphologies and morphological transitions of surfactant-inorganic-solvent systems confined in spherical pores. In this part, we focus on the effects of the interaction energies between the head groups and tail groups of surfactants,εHT, and the interaction between tail groups of surfactants and water,εTW, on the morphological transitions. The simulation results indicate that when asεHT increases the self-assembled morphologies of the surfactants confined in spherical pores show three different configurations:an irregularly Y-junction structure, transition structure and regularly spiral structure. On the other hand, asεTW changes, the self-assembled morphologies show two different configurations: irregularly Y-junction structure and regularly spiral structure. The morphologies of these novel structures are also a function of the pore diameter D,εHT andε-TW.2. Lattice MC simulations method was used to study the curvature induced morphologies of surfactants adsorbed on the surface of the hydrophilic solid-liquid interface. We study the adsorption behaviors of surfactants on the surface of flat nanomaterials and on cylindrical nanomaterials. We found that the morphology of H3T4 surfactant adsorbed on the flat nanomaterials is worm-like structure. However, when H3T4 surfactant adsorbed on the cylindrical nanomaterials, the morphologies show different structures. When the cylinder radius R=5 and 13, the morphologies of H3T4 surfactant adsorbed on the surface of cylindrical nanomaterials are linear chain-like micelle structures. While as R=7,9,11, the morphologies of H3T4 surfactants on the surface of cylindrical nanomaterials are Y-junction structures. In general, the morphologies of these novel structures are significantly affected by the curvature of solid surface.更多还原