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，在自然环境和工程系统中是一个非常重要的过程。表面上的矿物结垢，或矿物沉淀物的不需要的沉积，对许多工业过程提出了技术挑战。在膜基水处理中，聚合物膜的矿物结垢降低了膜通量，降低了能源效率，缩短了膜组件的使用寿命。在油气行业中，矿垢沉积在管道内表面会导致管道完全堵塞，影响油气生产。尽管聚合物固体基质在矿物结垢中的作用很重要，但人们对其了解甚少。本研究旨在了解聚合物的表面特征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。这项工作的发现将为水下水环境中抗结垢聚合物表面的设计提供信息，这将为那些矿物结垢影响系统性能和长期耐用性的行业带来显著的经济效益。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。这些研究人员将主持一个由学生主持的关于环境纳米科学的年度研讨会，并接待高中生实习生，并为当地高中生提供客座讲座。在反渗透、海水淡化、热交换器、石油和天然气生产等许多工业过程中，表面的矿物结垢或矿物沉淀物的沉积是一种普遍存在但又不需要的现象。减轻结垢的一种很有前景的策略是改变聚合物表面特性或在非聚合物表面涂覆聚合物涂层以使表面耐结垢。目前，在理解纳米尺度的相互作用和聚合物结垢初始阶段的物理化学过程方面存在很大的知识缺口。这种知识差距限制了抗结垢膜和表面聚合物涂层的合理开发。在这项研究中，研究人员将结合液相透射电子显微镜、石英晶体微天平实时测量结垢动力学以及理论建模来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：1)研究分子层组装聚酰胺膜的表面电荷和疏水性对矿物结垢率的影响；2)利用液相透射电子显微镜在纳米尺度上实时可视化和量化聚酰胺表面矿物成核动力学；3)推导纳米颗粒附着和成核动力学的理论模型，以确定纳米尺度的相互作用作为聚合物表面化学的函数，参与成核形成。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和研究生课程材料，主办学生联合举办的纳米材料和水专题讨论会，并加强代表性不足的学生对研究的参与。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识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.