Collaborative Research: Deciphering the nanoscale interactions during mineral nucleation and scale formation on polymer surfaces

矿物沉淀，或从溶液中形成固体矿物相，是自然环境和工程系统中非常重要的过程。表面上的矿物结垢或矿物沉淀物的不希望的沉积对许多工业过程提出了技术挑战。在基于膜的水处理中，聚合物膜的矿物质结垢降低膜通量，降低能量效率，并缩短膜组件寿命。在石油和天然气工业中，管道内表面上的矿物垢沉积可导致管道完全堵塞并中断石油和天然气生产。尽管其重要性，聚合物固体基质对矿物结垢的作用知之甚少。 本研究旨在了解聚合物的表面特性如何影响矿物垢的形成。研究人员将采用实验表征和理论分析相结合的方法来研究驱动聚合物基材上矿物垢形成的纳米级相互作用。这项工作的结果将为淹没水环境中的防垢聚合物表面的设计提供信息，这将为矿物结垢困扰系统性能和长期耐久性的行业带来显着的经济效益。该研究项目将通过乔治华盛顿大学和马里兰州大学的公众参与提供外展活动。研究人员将举办一个由学生主持的环境纳米科学年度研讨会，并接待高中生实习生，并为当地高中生提供客座讲座。表面上的矿物结垢或矿物沉淀物的不希望的沉积是许多工业过程中普遍存在但不希望的现象，包括反渗透、水脱盐、热交换器以及石油和天然气生产。减轻结垢的一个有希望的策略是改变聚合物表面特性或将聚合物涂层施加到非聚合物表面以使表面抗结垢。目前，有一个显着的知识差距，了解纳米级的相互作用和物理化学过程中的初始阶段的规模形成的聚合物。这种知识差距限制了防垢膜和表面聚合物涂层的合理开发。在这项研究中，研究人员将整合液相透射电子显微镜，使用石英晶体微量天平实时测量结垢动力学，以及理论建模，以建立二氧化硅和石膏在聚酰胺表面结垢过程中的成核机制。研究目的是：1）考察分子层层组装法制备的聚酰胺膜表面电荷和疏水性对矿物结垢速率的影响，2）采用液相透射电子显微术以纳米长度尺度真实的时间可视化和量化聚酰胺表面上的矿物成核动力学，以及推导出纳米颗粒附着和成核动力学的理论模型，以确定作为聚合物表面化学的函数的结垢形成中涉及的纳米级相互作用。这项工作的结果将有助于合理操纵纳米级矿物膜的相互作用，以防止工程聚合物在水环境中的矿物结垢。该项目的教育和推广方面将把研究成果纳入本科生和研究生课程材料，主办联合学生运行的纳米材料和水专题讨论会，并提高代表性不足的学生在研究中的参与。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Mineral precipitation, or the formation of solid mineral phases from solutions, is a process of great importance in the natural environment and engineered systems. Mineral scaling on surfaces, or the unwanted deposition of mineral precipitates, poses a technological challenge to many industrial processes. In membrane-based water treatment, mineral scaling of polymer membranes decreases membrane flux, diminishes energy efficiency, and shortens membrane module lifespan. In the oil and gas industry, mineral scale deposition on the interior surface of pipes can result in complete blockage of pipelines and disrupt oil and gas production. Despite its importance, the role of polymeric solid substrates on mineral scaling is poorly understood. This research aims to understand how the surface characteristics of polymers impact the formation of mineral scales. The investigators will employ combined experimental characterization and theoretical analysis to examine the nanoscale interactions that drive mineral scale formation on polymeric substrates. The findings of this work will inform design of anti-scaling polymer surfaces in submerged aqueous environments, which will bring significant economic benefits to industries in which mineral scaling plagues system performance and long-term durability. This research project will provide outreach activities through public engagement at both George Washington University and University of Maryland. The investigators will host a yearly student-run symposium on environmental nanoscience, and host high school student interns and deliver guest lectures to local high school students. Mineral scaling on surfaces, or the unwanted deposition of mineral precipitates, is a ubiquitous yet unwanted phenomenon in many industrial processes including reverse osmosis, water desalination, heat exchangers, and oil and gas production. One promising strategy for mitigating scaling is to modify polymer surface characteristics or apply polymer coatings to non-polymer surfaces to render the surface scaling resistant. Currently, there is a significant knowledge gap in understanding the nanoscale interactions and physicochemical processes in the initial stages of scale formation on polymers. This knowledge gap limits rational development of scaling-resistant membranes and surface polymer coatings. In this research, the investigators will integrate liquid phase transmission electron microscopy, real-time measurement of scale formation dynamics using quartz crystal microbalance, and theoretical modeling to establish nucleation mechanisms during scaling of silica and gypsum on polyamide surfaces. The research objectives are to 1) investigate the effect of surface charge and hydrophobicity of polyamide films prepared via molecular layer-by-layer assembly on mineral scaling rate, 2) employ liquid phase transmission electron microscopy to visualize and quantify mineral nucleation dynamics on polyamide surfaces in real time at the nanometer length scale and 3) derive theoretical models for nanoparticle attachment and nucleation kinetics to identify the nanoscale interactions involved in scale formation as a function of polymer surface chemistry. The results of this work will facilitate rational manipulation of nanoscale mineral-membrane interactions to prevent mineral scaling on engineering polymers in the aqueous environment. Educational and outreach aspects of the project will incorporate research findings into undergraduate and graduate course materials, host joint student-run nanomaterial and water symposia, and enhance the participation of underrepresented students in research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.