Measuring the Release of Nanoparticles from Polymer Nanocomposites using Single Particle ICPMS and Field Flow Fractionation ICPMS

1336168 Ranville概述：本研究提案描述了使用高灵敏度定量分析技术研究纳米TiO 2和CNT从聚合物纳米复合材料中释放的计划。大多数纳米颗粒（NP）最初将作为固相材料的组分（即，纳米产品）。最重要的纳米产品类型之一是聚合物纳米复合材料，其结合了诸如碳纳米管（CNT）、纳米银或纳米级金属氧化物的NP，这是由于它们能够增强聚合物性质，诸如导电性和承载能力。事实上，聚合物纳米复合材料已经出现在消费品中，如自行车、燃油管路的防静电部件以及电子和食品工业中使用的包装材料。研究聚合物纳米复合材料中NP释放的动机来自两个最重要的考虑：（i）关于纳米产品中NP释放的信息缺乏，尽管NP释放在确定环境中NP造成的风险方面发挥着至关重要的作用;和（ii）我们的初步结果表明NP确实可以从聚合物纳米复合材料中释放，NP释放可以用单粒子电感耦合等离子体质谱法（spICPMS）检测。智力优点：拟议的研究将通过确定控制NP释放的程度，性质和速率的因素，改变我们对NP从纳米产品释放的理解。这将通过制备和表征含有纳米TiO 2或CNT的聚合物纳米复合材料来实现，其中基质的身份以及表面化学和NP负载将变化。然后，这些定义明确的复合材料将经受潜在的NP释放场景和“加速老化”条件，包括光解、机械应力、热循环和暴露于苛刻的氧化剂。然后将评估从纳米复合材料释放的NP的浓度和性质。进行NP释放研究的一个主要障碍是需要测量极低（例如ng/L）浓度的NP。为了克服这个障碍，我们将使用spICPMS和场流分馏（FFF-ICPMS）来确定纳米二氧化钛的粒度分布和ng/L浓度。虽然通过测量碳信号来检测spICPMS中的CNT是模糊的，但是PI已经表明嵌入的金属NP可以作为CNT的替代物。这种方法使我们能够使用spICPMS来检测从聚合物纳米复合材料中释放的CNT。这项工作的一个关键组成部分是进一步改进用于碳纳米管定量分析的spICPMS方法，并将spICPMS和FFF-ICPMS结合起来，以确定释放的纳米颗粒的物理形态。通过将最先进的检测能力整合到实验计划中，其中明确定义的聚合物复合材料暴露于潜在的释放场景，我们将能够评估纳米复合材料组合物和可变环境条件对NP释放的程度和速率的影响。这些数据将使我们能够确定释放机制以及聚合物纳米复合材料的特性和暴露条件下，NP释放是最有可能（和最不可能）发生。这些新的信息不仅将提高风险评估和生命周期分析模型的准确性，而且还将为未来纳米产品的设计提供信息，这些纳米产品将保留商业价值，而不会对环境健康和安全产生不利影响。开发的分析方法和实验方案也将为研究人员提供一个平台，以检查NP从其他纳米产品中的释放。谁参加这个固有的跨学科研究项目的学生将获得一套独特的技能，结合了环境科学与工程，材料化学和分析科学的元素，为他们提供了许多就业机会。项目成果将通过在国家科学会议和地方学院的演讲以及在同行评审的期刊上发表文章的方式传播。通过继续在国际会议上讲授关于spICPMS应用的短期课程，将进一步加强该项目的科学影响。教育推广将建立和扩大我们以前的活动，让4年制大学的本科生参与研究，并为暑期研究项目引进高中教师。这个项目也将被用来作为一种工具，将纳米产品的使用和影响的概念纳入现有的K-12教育模块，我们已经开发，并已成功地在几个科罗拉多高中使用。

1336168RanvilleOverview: This research proposal describes plans to study the release of nano-TiO2 and CNTs from polymer nanocomposites using highly sensitive quantitative analytical techniques. Most nanoparticles (NPs) will enter the environment initially as components of solid phase materials (i.e., nanoproducts). One of the most important types of nanoproducts are polymer nanocomposites that incorporate NPs such as carbon nanotubes (CNTs), nano-silver, or nano-scale metal oxides due to their ability to enhance polymer properties such as conductivity and load bearing capabilities. Indeed, polymer nanocomposites are already present in consumer products such as bicycles, anti-static parts for fuel lines, and packaging materials used in the electronic and food industries. Motivation for studying NP release from polymer nanocomposites is derived from two overriding considerations: (i) the paucity of information on the release of NPs from nanoproducts, despite the crucial role that NP release will play in determining the risk posed by NPs in the environment; and (ii) our initial results which indicate that NPs can indeed be released from polymer nanocomposites, and that NP release can be detected with single particle inductively coupled plasma mass spectrometry (spICPMS).Intellectual Merit: The proposed research will transform our understanding of NP release from nanoproducts by identifying the factors that control the extent, nature, and rate of NP release. This will be accomplished by preparing and characterizing polymer nanocomposites containing nano-TiO2 or CNTs, where the identity of the matrix as well as the surface chemistry and NP loading will be varied. These well-defined composites will then be subjected to potential NP release scenarios and "accelerated aging" conditions that include photolysis, mechanical stress, thermal cycling and exposure to harsh oxidants. The concentration and nature of NPs released from the nanocomposites will then be evaluated. A major obstacle in conducting NP release studies is the need to measure extremely low (e.g. ng/L) concentrations of NPs. To overcome this obstacle, we will use spICPMS and field-flow fractionation (FFF-ICPMS) to determine particle size distributions and ng/L concentrations of nano-TiO2. Although detecting CNTs in spICPMS by measuring the carbon signal is ambiguous, the PIs have shown that embedded metal NPs can serve as proxies for CNTs. This approach allowed us to use spICPMS to detect CNT released from polymer nanocomposites. A key component of the work is to further improve spICPMS methodology for quantitative analysis of CNTs and to combine spICPMS and FFF-ICPMS to identify the physical form of released NPs.Broader Impacts: By integrating state-of-the-art detection capabilities into an experimental plan where well-defined polymer composites are exposed to potential release scenarios, we will be able to evaluate the effects of both nanocomposite composition and variable environmental conditions on the extent and rate of NP release. These data will enable us to identify release mechanisms as well as the polymer nanocomposite characteristics and the exposure conditions where NP release is most (and least) likely to occur. This new information will improve not only the accuracy of risk assessment and life cycle analysis models, but also inform the design of future nanoproducts that retain commercial value without contributing to adverse environmental health and safety effects. Analytical methods and experimental protocols developed will also provide a platform for researchers to examine NP release from other nanoproducts. Students who participate in this inherently interdisciplinary research project will acquire a unique skill set that incorporates elements of environmental science and engineering, materials chemistry, and analytical science, providing them with many career opportunities. Project results will be disseminated through presentations at national scientific meetings and local colleges as well as publications in peer-reviewed journals. The scientific impact of this project will be further enhanced by continuing to teach short courses on spICPMS applications at international meetings. The educational outreach will build on and expand our previous activities of involving undergraduates from 4-year colleges in research and in bringing in high school teachers for summer research programs. This project will also be used as a vehicle to incorporate concepts of nanoproduct use and impact into existing K-12 educational modules that we have developed and which have been used successfully in several Colorado high schools.