Confinement Effects and Active Nanostructure Control in Amphiphilic Systems

项目编号：CBET: 0730392首席研究员：Arijit bose大学/机构：罗德岛大学标题：两亲体系中的约束效应和主动纳米结构控制智力价值本项目是一个实验项目，旨在了解在系统增加三维和二维约束条件下两亲自组装过程的影响。由于在高度受限域中排除的体积熵效应变得显著，它们可以在控制两亲性体系中有组织纳米结构形成的热力学中发挥重要作用。该项目提出假设，这些被排除的体积效应的熵贡献以及与边界面的远程相互作用可以在体积系统中不存在的受限情况下产生一系列平衡形态。在我们的实验室中，我们观察到，对于CTAB/HDBS模型阳离子离子体系，聚苯乙烯乳胶球产生的三维约束显著减少了在填充珠之间的空隙中形成的囊泡的大小。这些结果与一个简单的热力学模型显示了接近的定量一致，该模型同时考虑了焓和自由体积熵对吉布斯自由能变化的贡献。在拟议的研究中，有意选择了一系列模型两亲系统和约束表面，从本质上不吸收表面活性剂分子到强吸收表面活性剂分子。小角中子散射（SANS）、低温透射电子显微镜（cryo-TEM）和动态光散射将用于评估和理解纳米结构的形态。他们将利用在受限系统中可用的高比表面积以及边界之间的小长度尺度来主动控制纳米结构。这些实验将为两亲体系在三维和二维约束条件下的微观结构演化提供重要的新认识。这项研究将有助于为软胶体材料通过高度受限领域的几种技术的发展提供基础，包括血管和皮肤中药物输送载体的命运，使用表面活性剂驱油从页岩中回收石油，去除率和胶束增强超滤。这项工作为研究生提供了一个获得SANS和低温透射电镜经验的机会，这是一种不寻常的组合。本科生将获得使用低温透射电镜的经验。这项研究的内容将直接纳入PI定期为学生和行业参与者开设的“界面和胶体现象进展”课程。为了让更多的学生接触到电子显微镜，我们校园的新TEM将可以上网。互联网电子显微镜将通过URI正在制定的外展计划提供给当地的高中生和科学教师。此外，PI将在他的实验室接待一名少数民族高中生，在夏天完成一个独立的子项目。通过该项目提供的教师指导，已经由私人捐款资助，已经成功地鼓励高中生考虑从事科学和技术事业。他们将与美国国家科学基金会资助的东北研究生教育和教授联盟（NEAGEP）项目密切合作，为该项目招募一名代表性不足的学生。URI是NEAGEP的成员之一，并在校园内开展了一个项目，以积极解决在科学、数学和工程（SME）领域获得博士学位的少数族裔学生的短缺问题。URI在毕业生处设有一个行政的中小企业招聘及留用组。

Proposal Number: CBET: 0730392 Principal Investigator: Arijit BoseUniversity/Institution: University of Rhode IslandTitle: Confinement Effects and Active Nanostructure Control in Amphiphilic Systems Intellectual merit This project is an experimental program to understand ramifications to the amphiphilic self-assembly process under conditions of systematically increasing three- and two-dimensional confinement. Because excluded volume entropic effects in highly confined domains become significant, they can contribute strongly to the thermodynamics governing the formation of organized nanostructures in amphiphilic systems. The project proposes hypothesize that entropic contributions from these excluded volume effects as well as long-range interactions with bounding surfaces can produce a range of equilibrium morphologies in confined situations that are not present in bulk systems. The proposed experiments follow recent results in our laboratory, where we have observed that for a CTAB/HDBS model catanionic system, three-dimensional confinement produced by polystyrene latex spheres dramatically reduces the size of vesicles formed in the void spaces between the packed beads. These results show near quantitative agreement with a simple thermodynamic model that accounts for both enthalpic and free volume entropic contributions to the change in Gibbs free energy. In the proposed research, a range of model amphiphilic systems and confinement surfaces are deliberately chosen to vary from essentially non-absorbing to strongly absorbing for the surfactant molecules. Small Angle Neutron Scattering (SANS), Cryogenic Transmission Electron Microscopy (cryo-TEM), and dynamic light scattering to evaluate and understand nanostructure morphology will be used. They will exploit the high specific surface area available in confined systems as well as the small length scale between boundaries for active control of nanostructures. These experiments will provide important new understanding of microstructure evolution in amphiphilic systems underconditions of three- and two-dimensional confinement.Broader Impact This research will help provide a fundamental basis for the development of several technologies where soft colloidal materials are passed through highly constrained domains, including the fate of drug delivery vehicles in blood vessels and in the skin, recovery of oil from shale using surfactant flooding, detergency and micellar enhanced ultrafiltration. The work provides an opportunity for graduate students to gain experience in SANS and cryo-TEM, a combination that is unusual. Undergraduates will get experience with cryo-TEM. Contents from this research will be incorporated directly into a 'Advances in Interfacial and Colloidal Phenomena' course taught regularly by the PI for students and industry participants. In order to expose more students to electron microscopy, the new TEM arriving on our campus will be internet-enabled. The internet electron microscope will be offered to local high school students and science teachers through an outreach program being developed at URI. In addition, the PI will host a minority high school student in his laboratory over the summer, to work on an independent sub-project. The faculty mentorship provided through this program, already funded through private donations, has been successful in encouraging high school students to think about careers in science and technology. They will work closely with our NSF-funded Northeast Alliance for Graduate Education and the Professoriate (NEAGEP) program to recruit an underrepresented student for this project. URI is a member of NEAGEP and has a program in place on campus to proactively address the shortage of underrepresented minority students receiving Ph.D.s in the sciences, mathematics and engineering (SME). URI has a staffed administrative SME Recruitment and Retention Unit within the Graduate.