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.

技术摘要这一奖项支持凝胶弹性和静电耦合的理论和数值研究。 静电在现代材料的开发中起着至关重要的作用，包括用于水过滤的膜，用于诊断的功能化纳米颗粒，用于基因治疗的聚电解质复合物，用于药物输送的纳米凝胶，锂离子电池和新型设备。这些系统通常需要支持异质弹性介质，其中可以传输信息，例如双连续膜或凝胶。这些材料的许多功能以及生物凝胶的功能是由电荷和组成异质性引起的。 在任意形状的异质介质中，解决静电和弹性问题都有巨大的挑战。 PI旨在开发方法来确定异质凝胶的性质，包括在经典平均野外模型中忽略的效果，例如离子的硬核，介电不匹配和弹性能。 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在同一模拟时间步长中响应； （ii）使用连续弹性模型来形成与局部异质性耦合的凝胶中弹性效应的表述，以描述由局部异质性引起的凝胶形变化。研究中将使用多种技术，包括密度官能方法，粗糙的分子 - 纤维 - 分子 - 动力学模拟和有限的元素方法。 对静电学的理解将为凝胶自组装和合成材料的设计提供信息。 PI与墨西哥复杂电解质的专家合作。 PI和她的墨西哥合作者的综合努力将有助于设计智能凝胶清洁水，这在墨西哥和美国都是重要的社会问题。此外，通过监督代表性不足的族裔群体的学生和博士后，PI致力于继续增加科学的多样性。她还致力于通过参加西北大学的外展计划来教育公众，并吸引中学生参与科学研究。本科摘要奖支持有关凝胶弹性和静电的理论和数值研究。 凝胶是悬浮在液体中但表现出固体的某些机械性能的扩张交联聚合物分子的网络。 分子的一部分通常带有电荷，并且电荷的相互作用控制分子的组装成凝胶和凝胶的性质。该奖项为如何正确描述凝胶中的静电相互作用及其与材料的弹性特性的相互作用提供了研究。 凝胶用于多种应用中。这项研究还适用于其他软材料和系统。静电相互作用的适当理论描述与异质软材料中的弹性效应结合在一起对于设计新材料（例如用于过滤水的膜以使其安全饮用的膜）非常重要。 该研究将与墨西哥的专家合作进行。 PI参与了她的大学的推广工作，并致力于扩大代表性不足的群体的代表。