The behaviour of polymer colloids in freshwater flow environment

监测环境(水、土壤、生物体)中微塑料的存在已经获得了相当大的吸引力，出现了许多出色的举措。最近的一个例子是加利福尼亚州水资源管理委员会已经批准了饮用水测试程序。塑料颗粒的存在可能会进入所有生物的食物链，并可能产生负面影响。在这个项目中，我们将观察直径范围为20 nm-5微米的颗粒，因此大大小于5 mm的上限阈值，换句话说，重点关注亚微米范围的塑料纳米颗粒。在自然界中，它们以天然聚合物乳胶(橡胶树、蒲公英)的形式存在。自20世纪30年代以来，以聚合物分散体形式的人造聚合物纳米颗粒被大量生产，用于涂料/粘合剂、造纸、医疗诊断测试等。这些颗粒通常太小，无法用明亮的光学显微镜进行跟踪。我们的目标是制备一系列模型聚合物分散体，其中的颗粒具有不同的大小、形状、相对分子质量和化学组成以及胶体稳定性。第二个重点是制造不容易降解的颗粒，以及可堆肥/可降解的颗粒。为此，我们将使用最新的聚合物分散生产技术，如(微型)乳液聚合和灾难性的相转化乳化来制备人造乳胶。然后，我们将研究控制颗粒运动行为(水流动力学、弥散和扩散)、滞留和积累行为(附着、拥挤、混凝、成膜、分解/分解)的潜在物理机制，包括滞水池、河流和湿地。这一项目将首次提供更好的理解，了解这种小颗粒在水生领域中的行为，它们将在哪里居住，以及它们如何潜在地被降解为无害的取代基。该项目提供的新见解将使人们能够理解微塑料和纳米塑料在具有挑战性的湍流系统中的传输和命运的动态。因此，该项目将结合多相聚合物化学、胶体科学和流体动力学，通过了解和量化塑料纳米颗粒的运输和去向，为环境保护和综合流域管理提供一个步骤。聚合物纳米塑料将通过非均相自由基聚合技术来制备，其中(微型)乳液聚合与可逆失活自由基聚合相结合，以调节摩尔质量分布、化学组成、胶体稳定性以及粒子形状和结构。将通过暗场和荧光显微镜(独眼巨人传感器)、拉曼光谱和离线分析方法(如流体动力分离)和元素分析技术(原子吸收、XRF、电感耦合等离子体质谱)相结合，开发水和模型土壤中颗粒的跟踪方法。将使用开源计算流体动力学建模程序包(OpenFOAM)来研究跨不同水流域的颗粒运动行为的模型开发。将在该项目内开发的算法将与现有的多相流模型相结合，以模拟各种水文条件下的污染物运移。颗粒降解将通过动力学模型(常微分方程组和蒙特卡罗方法)进行研究。

The monitoring of the presence of microplastics in the environment (water, soil, organisms) has gained considerable traction, with a plethora of excellent initiatives. A recent example is that Californian state water resources control board has approved procedures for testing drinking water. The presence of plastic particles can enter the food chain for all living species, and potentially have a negative impact. In this project we will look at particles in the diameter range of 20 nm - 5 micrometer, so considerably smaller than the 5 mm upper threshold, in other words a focus on the sub-micron range, plastic nanoparticles. In nature these exist in the form of a natural polymer latex (rubber trees, dandelions). Manmade polymer nanoparticles, in the form of polymer dispersions are produced in vast quantities since the 1930s for coatings/adhesives, paper production, medical diagnostic tests, to name but a few. These are often too small to be tracked with brightfield light microscopy.We aim to fabricate a collection of model polymer dispersions in which the particles have varied characteristics in size, shape, molecular weight and chemical composition, and colloidal stability. A secondary focus is to make particles that will not degrade easily, and particles that are compostable/hydrolysable. For this we will use the latest polymer dispersion production techniques, such as (mini-) emulsion polymerization, and catastrophic phase inversion emulsification to prepare artificial latexes. We then will study the underlying physical mechanisms that govern the particles' motility behavior (flow hydrodynamics, dispersion and diffusion), residence and accumulation behavior (adhesion, crowding, coagulation, film formation, disintegration/decomposition) in model aquatic systems including stagnant pond, river, and wetland. This project, for the first time, will provide a better understanding of how such small particles will behave across aquatic domains, where they will reside, and how they potentially can be degraded into harmless substituents. The new insights offered by this project will enable understanding the dynamics of micro- and nanoplastics transport and fate in challenging turbulent flow systems. Hence, this project will provide a step change in environmental protection and integrated catchment management by understanding and quantifying the transport and fate of plastic nanoparticles.The project will combine heterogeneous polymer chemistry, colloid science, and fluid dynamics. Polymer nanoplastics will be prepared by heterogeneous radical polymerization techniques, where (mini-) emulsion polymerization is combined with reversible deactivation radical polymerization developments, to tune molar mass distribution, chemical composition, colloidal stability, and particle shape and architecture. Tracking methods of the particles in water and model soils will be developed through combination of darkfield and fluorescence microscopy (Cyclops sensors), Raman spectroscopy, and off-line analysis methods, such as hydrodynamic fractionation, and elemental analysis techniques (atomic absorption, XRF, ICP-MS). Model development of particle motility behavior across different aquatic flow domains will be studied using open-source computational fluid dynamic modelling packages (OpenFOAM). The algorithms which will be developed within this project will be coupled with existing multi-phase flow models in order to simulate pollutant transport under various hydrologic conditions. Particle degradation will be studied by kinetic modelling (ODEs and Monte Carlo approaches).