Organization of charged molecules in heterogeneous media

异质介质中带电分子的组织

• 批准号: 1309027
• 负责人: Monica Olvera
• 金额: $ 30万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-15 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1309027&HistoricalAwards=false
• 关键词: Organization; charged; molecules; heterogeneous; media

TECHNICAL SUMMARYThis award supports theoretical and numerical research on the coupling of elasticity and electrostatics of gels. Electrostatics plays a critical role in the development of modern materials including membranes for water filtration, functionalized nanoparticles for diagnostics, polyelectrolyte complexes for gene therapy, nanogels for drug delivery, lithium-ion batteries and novel devices. These systems often require the support of a heterogeneous elastic medium where the information can be transferred such as a bicontinuous membrane or a gel. Many of the functions of these materials, as well as of biological gels, result from charge and composition heterogeneities. There are great challenges in both, solving electrostatics and elasticity problems in heterogeneous media of arbitrary shapes. The PI aims to develop ways to determine the properties of heterogeneous gels including effects neglected in classical mean field models such as the hard core of the ions, the dielectric mismatch and the elastic energy. More specifically, the PI will: (i) study the effect of hard-core interactions in dense ionic gels via a non-linear density-functional theory that accounts properly for long- and short-range interactions and will test the results via computer simulations;(ii) analyze the effect of local dielectric heterogeneities in the presence of divalent ions or absorbing molecules via an energy variational principle that enables one to update charges and the medium's response in the same simulation time step; and(ii) develop a formulation of elasticity effects in gels coupled to local heterogeneities using a continuum elasticity model to describe the gel-shape changes induced by local heterogeneities.A variety of techniques will be used in the research including a density-functional approach, coarse-grained molecular-dynamics simulation, and finite-elements methods. The understanding of electrostatics will inform research on self-assembly of gels and the design of synthetic materials. The PI collaborates with experts in complex electrolytes in Mexico. The combined efforts of the PI and her Mexican collaborators will aid the design of smart gels for cleaning water, which is an important societal problem in both Mexico and the US. Moreover, the PI is committed to continue increasing diversity in science by supervising students and postdocs from underrepresented ethnic groups. She is also committed to educate the public and engage middle and high school students in scientific research by participating in outreach programs at Northwestern University.NONTECHNICAL SUMMARYThis award supports theoretical and numerical research on the coupling of elasticity and electrostatics of gels. A gel is a network of dilutely cross-linked polymer molecules suspended in liquid but exhibiting some of the mechanical properties of a solid. Parts of the molecules generally carry electric charges, and the interactions of the charges govern both the assembly of the molecules into a gel and the gel's properties. This award funds research on how to properly describe electrostatic interactions in gels and their interplay with the elastic properties of the material. Gels are used in a wide variety of applications. This research will also be applicable to other soft materials and systems. A proper theoretical description of electrostatic interactions combined with elastic effects in heterogeneous soft materials will be important for the design of new materials, such as membranes for filtering water to make it safe for drinking. The research will be carried out in collaboration with experts in Mexico. The PI is involved in outreach efforts at her university and is committed to broadening representation from underrepresented groups.

该奖项支持对凝胶的弹性和静电耦合的理论和数值研究。 静电学在现代材料的开发中起着关键作用，包括水过滤膜、诊断用功能化纳米颗粒、基因治疗用纳米复合物、药物输送用纳米凝胶、锂离子电池和新型设备。这些系统通常需要一种异质弹性介质的支持，在这种介质中可以传递信息，例如双连续膜或凝胶。这些材料以及生物凝胶的许多功能是由电荷和组成的不均匀性引起的。 在任意形状的非均匀介质中求解静电学和弹性力学问题都面临着巨大的挑战。PI的目的是开发方法来确定非均质凝胶的性质，包括在经典的平均场模型，如离子的硬核，介电失配和弹性能忽略的影响。更具体地说，PI将：（i）通过非线性密度泛函理论研究致密离子凝胶中硬核相互作用的影响，该理论适当考虑了长距离和短距离相互作用，并将通过计算机模拟测试结果;（二）通过能量变分原理分析二价离子或吸收分子存在下局部介电不均匀性的影响，该原理使人们能够更新电荷，介质的响应在同一个模拟时间步长;和（ii）开发一个配方的弹性效应耦合到本地heterogeneities使用连续弹性模型来描述凝胶形状的变化引起的本地heterogeneities。各种技术将被用于研究，包括密度泛函方法，粗粒度的分子动力学模拟，和有限元方法。 对静电学的理解将为凝胶自组装和合成材料设计的研究提供信息。 PI与墨西哥的复杂电解质专家合作。 PI和她的墨西哥合作者的共同努力将有助于设计用于清洁水的智能凝胶，这是墨西哥和美国的一个重要社会问题。此外，PI致力于通过监督来自代表性不足的族裔群体的学生和博士后来继续增加科学的多样性。她还致力于教育公众，并通过参加西北大学的外展计划吸引初中和高中学生参与科学研究。非技术性总结该奖项支持凝胶弹性和静电耦合的理论和数值研究。 凝胶是悬浮在液体中的稀释交联聚合物分子的网络，但表现出固体的一些机械性质。 部分分子通常带有电荷，电荷的相互作用决定了分子组装成凝胶的过程和凝胶的性质。该奖项资助如何正确描述凝胶中的静电相互作用及其与材料弹性特性的相互作用。 凝胶用于各种各样的应用中。该研究也适用于其他软材料和系统。在异质软材料中结合弹性效应的静电相互作用的适当理论描述对于新材料的设计将是重要的，例如用于过滤水以使其安全饮用的膜。 这项研究将与墨西哥的专家合作进行。PI参与了她所在大学的外联工作，并致力于扩大代表性不足群体的代表性。