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。表面的矿物结垢或矿物沉淀物的不必要沉积给许多工业过程带来了技术挑战。在基于膜的水处理中，聚合物膜的矿物结垢会降低膜通量、降低能源效率并缩短膜组件的使用寿命。在石油和天然气行业，管道内表面的矿物垢沉积可能导致管道完全堵塞并扰乱石油和天然气生产。尽管聚合物固体基质很重要，但人们对它在矿物结垢方面的作用却知之甚少。 这项研究旨在了解聚合物的表面特性如何影响矿物鳞片的形成。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质上矿物尺度形成的纳米级相互作用。这项工作的结果将为水下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用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大学的公众参与提供外展活动。研究人员将每年举办一次由学生主办的环境纳米科学研讨会，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需要的沉积是许多工业过程中普遍存在但不希望出现的现象，包括反渗透、海水淡化、热交换器以及石油和天然气生产。一种有前途的减轻结垢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具有抗结垢能力。目前，在理解聚合物结垢初始阶段的纳米级相互作用和物理化学过程方面存在显着的知识差距。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、使用石英晶体微天平实时测量结垢形成动力学以及理论模型，以建立聚酰胺表面二氧化硅和石膏结垢过程中的成核机制。研究目标是：1）研究通过分子层层组装制备的聚酰胺薄膜的表面电荷和疏水性对矿物结垢率的影响；2）采用液相透射电子显微镜在纳米长度尺度上实时可视化和量化聚酰胺表面上的矿物成核动力学；3）推导出纳米颗粒附着和成核动力学的理论模型，以识别作为聚合物表面化学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-膜相互作用，以防止水环境中工程聚合物上的矿物结垢。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中，主办学生联合举办的纳米材料和水研讨会，并提高代表性不足的学生对研究的参与。该奖项反映了 NSF 的法定使命，并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，被认为值得支持。

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.