Confinement Effects and Active Nanostructure Control in Amphiphilic Systems

建议编号：CBET：0730392首席研究员：Arijit Bose大学/研究所：罗德岛大学题目：两亲性系统中的限制效应和主动纳米结构控制这个项目是一个实验计划，旨在了解在系统地增加三维和二维限制条件下对两亲性自组装过程的影响。由于在高度受限的区域中排除的体积熵效应变得显著，它们可以对控制两亲体系中有序纳米结构的形成的热力学做出重大贡献。该项目提出的假设是，这些被排除的体积效应以及与束缚表面的长程相互作用所产生的熵贡献可以在受限情况下产生一系列在大体积系统中不存在的平衡形态。我们的实验遵循了我们实验室最近的结果，我们观察到对于CTAB/HDBs模型的阴离子体系，由聚苯乙烯乳胶球产生的三维限制极大地减少了在填充微珠之间的空隙中形成的小泡的尺寸。这些结果与一个简单的热力学模型几乎是定量一致的，该模型同时考虑了自由能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，刻意选择了一系列模型两亲性体系和限制表面，以从基本上不吸收表面活性剂分子到强吸收表面活性剂分子。将使用小角中子散射(SANS)、低温透射电子显微镜(Cryo-TEM)和动态光散射来评估和了解纳米结构的形态。他们将利用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。这些实验将对三维和二维限制条件下两亲性体系的微观结构演变提供重要的新理解。广泛影响这项研究将有助于为软胶体材料通过高度受限区域的几种技术的发展提供基本基础，包括药物输送载体在血管和皮肤中的去向，表面活性剂驱从页岩中回收石油，清净和胶束增强超滤。这项工作为研究生提供了一个在SANS和低温瞬变电磁方面获得经验的机会，这是一种不寻常的组合。本科生将获得低温瞬变电磁的经验。这项研究的内容将直接纳入由PI为学生和行业参与者定期讲授的一门课程--“界面和胶体现象进展”。为了让更多的学生接触到电子显微镜，到达我们校园的新的电子显微镜将启用互联网。互联网电子显微镜将通过URI正在开发的一个推广计划提供给当地的高中生和科学教师。此外，PI将在夏天在他的实验室接待一名少数族裔高中生，从事一个独立子项目的工作。通过这个项目提供的教师指导，已经由私人捐款资助，成功地鼓励高中生考虑在科学和技术领域的职业。他们将与美国国家科学基金会资助的东北研究生教育联盟和教授(NEAGEP)计划密切合作，为这个项目招收一名代表性不足的学生。URI是NEAGEP的成员，并在校园内实施了一项计划，积极解决缺乏代表性的少数民族学生获得科学、数学和工程博士学位(SME)的问题。URI在毕业生内部设有一个行政管理中小企业招聘和留用股。

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.