【作者】 杨逸群；

【导师】 刘晓亚；

【作者基本信息】 江南大学 ， 材料学， 2011， 硕士

【摘要】 近年来,双亲性嵌段、无规共聚物自组装的理论研究工作已经取得了令人瞩目的成绩。然而,自组装胶束的应用研究主要集中于对胶束结构性能的精确调控,实验步骤繁琐,实验条件苛刻。如何进一步拓展聚合物自组装胶束的应用,已然成为自组装界科学家们关注的热点之一。最近,各种无机、有机纳微米粒子的多级组装为自组装胶束的应用拓展提供了可行性思路以及模型。多级组装的过程不仅能结合一级组装体已有的优势,并且空间上的多维度排布或熔并能够赋予所得多级组装体新的性能及应用。微纳米粒子在表面或界面上的有序排布主要基于自组装或诱导组装。本课题设计合成具有不同结构性能的双亲性无规及交替共聚物,以它们自组装所得到的纳米胶束(一级组装体)为构筑基元,分别研究它们受界面张力驱动在油水界面的二次组装,以及受介电场力诱导在电极基材表面的沉积成膜,由此开拓双亲性共聚物自组装胶束在乳化和传感领域的应用。具体研究内容包括以下两个部分:1.交替共聚物P(St-alt-Ma-Dopa)的多级组装及乳化应用通过普通自由基共聚合成交替共聚物聚(苯乙烯-alt-马来酸酐) P(St-alt-Man),并用多巴胺氨解得到双亲性共聚物P(St-alt-Ma-Dopa)。在选择性溶剂(DMF/水)中,对P(St-alt-Man)及P(St-alt-Ma-Dopa)进行溶液自组装,得到稳定的球形纳米胶体粒子。P(St-alt-Ma-Dopa)胶体粒子具有一定的表面活性,在界面张力的驱动下,再次组装排布于油水界面。因此,在两次组装过程中,该胶体粒子可作为一种新型的颗粒乳化剂,用于制备稳定的Pickering乳液,即以P(St-alt-Ma-Dopa)胶体溶液为水相,甲苯为油相,均质后可得到稳定的水包油型Pickering乳液。一级组装所制备的P(St-alt-Ma-Dopa)胶体粒子具有盐浓度和pH响应性。其粒径和zeta电位在不同盐浓度和pH值条件下呈相反的变化规律。以芘为探针,采用荧光光谱法表征了P(St-alt-Ma-Dopa)胶体粒子的亲疏水性,结果表明胶体粒子的亲水性随pH值的增大而增强,随溶液盐浓度的增大而略微减弱。胶体粒子的盐浓度和pH值响应性也影响其在油水界面的再次排布组装,以及作为颗粒乳化剂的乳化性能。2.电诱导分子印迹聚合物胶束(MIPMs)的组装及其在MIP传感器中的应用以丙烯酸酯类单体和苯乙烯为原料,合成可光交联的双亲性无规共聚物。用乳酸酸化后,以葡萄糖为模板分子,在乙二醇单丁醚/水中,该共聚物自组装得到荷正电的,印迹有葡萄糖的胶束粒子,其形貌、尺寸由动态光散射(DLS)和透射电镜(TEM)表征确定。在负电场诱导下,组装胶束向工作电极泳动,并最终在电极表面沉积成膜。整个过程即电诱导双亲性共聚物的多级组装。结合组装胶束粒径及Zeta电位随pH值的变化规律,初步推断了胶束电沉积的机理。所形成的沉积膜经过光交联后,成为结构稳定的分子印迹膜(MIP Film),萃取其中的模板分子,其所修饰的工作电极即成为分子印迹传感器(MIP sensors),对模板分子具有良好的选择性和响应性。检测结果表明,该传感器对葡萄糖的线性响应范围介于0.2到8 mmol/L,检测下限为0.05 mmol/L,检测上限为10 mmol/L。得益于聚合物的光交联,印迹膜及其内部分子识别位穴被锁定,因此该传感器显示出优异的稳定性。综上,本课题研究从两个方面证实了双亲性共聚物多级组装的优势,为自组装技术的应用提供了新的思路。更多还原

【Abstract】 Currently, the research on self-assembly of the amphiphilic block/random copolymers has obtained a lot of remarkable achievements. However, the applications of self-assembled micelles focus on the design and control of special micelle structures which require multi-step experiments, restrict reaction conditions, and thus limit the utilization. How to open the next door of self-assembly micelles application has been the key research of the relevant field. Recently, hierarchical assembly of different kinds of inorganic or organic micro/nanoparticles provides researchers with new ideas and models. Not only embraced the advantages of first-aggregates, but hierarchical assembly also provided new characters and functions for the resulted hierarchical aggregates.The micro/nanoparticles’ordered arrangements on the surface or in the interface were based on self-assembly or induced-assembly. In this work, the first-aggregates from amphiphilic copolymers self-assembly were used as building blocks. Their behaviors of hierarchical assembly in oil/water interface triggered by interfacial tension, or depositing on the electrode surface induced by applied electric field, were studied respectively, and thus develop new utilizations of the amphiphilic copolymers’hierarchical assembly in emulsification and the field of sensorsThe detailed experiments are described as follows:1. Hierarchical assembly and emulsification of P(St-alt-Ma-Dopa)Using toluene as solvent, an alternating copolymer P(St-alt-Man) was prepared by free radical polymerzation which then underwent ammonolysis with dopamine to obtain an amphiphilic alternating copolymer P(St-alt-Man-Dopa). In selective solvent, P(St-alt-Man) and P(St-alt-Ma-Dopa) self-assembled into stable spherical colloid particles. The P(St-alt-Ma-Dopa) colloid particles showed good surface activity, and thus can further assembled in oil/water interface under the introduce of interfacial tension. Hence, in the process of assembly, the P(St-alt-Ma-Dopa) colloid particles can be used as a novel kind of particle emulsifiers--with P(St-alt-Ma-Dopa) solution as water phase and toluene as oil phase, stable Pickering oil-in-water emulsions were produced. The salinity and the pH value of the aqueous dispersion have different influence on the diameter and the zeta potential of P(St-alt-Man-Dopa) colloid particles. The hydrophilicity of the P(St-alt-Man-Dopa) colloid particles was determined by fluorescence technique using pyrene as probe, and the result showed that the hydrophilicity increased with the increase of pH and decreased slightly with the increase of salinity. The influences by salinity and pH value went on impact the further self-assembly and arrangement of these colloid particles on the oil/water interface, and their emulsification using as Pickering emulsifiers.2. Assembly of MIPMs induced by electric field and its application in MIP sensorsA photo-crosslinkable amphiphilic random copolymer was sythesised from acrylate monomers and styrene. After being acidified with lactic acid, this copolymer was self-assembled into molecularly imprinted polymeric micelles (MIPMs) in the selective solvent butoxyethanol/water with the attendance of template molecule glucose. The morphology and size of the MIPMs were measured by Dynamic Laser Scattering (DLS) and Transmission Electron Microscopy (TEM). Under the introduce of negative electric field, MIPMs swam to working electrode, deposited and ultimately transformed into a film on the electrode surface. The whole process was so called the electric field induced hierarchical assembly of amphiphilic copolymer. The mechanism of electrodeposition was primarily deduced by analyzing the results of Zeta potential. The structure of the resulted MIP film was locked by UV crosslinking. After extracting the template molecule glucose, the electrode became the MIP sensor and has good selectivity and response to glucose. The detections showed that the MIP sensor has linear response ranged from 0.2 mM to 8 mM, with a detection limit of 0.05 mM and an upper limit of 10 mM. Thanks to photo-crosslink of the copolymer which locked the recognition cavities in the MIP film, the MIP sensors show good stability and reproducibility.To sum up, this work explored the advantages of amphiphilic copolymer hierarchical assembly, and provided inspirations for the applications of self-assembly techniques.更多还原