Sahle-Demessie Endalkachew, Han Changseok, Varughese Eunice, Acrey Brad, Zepp Richard
U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solution and Emergency Response, Cincinnati, OH, 45268, USA.
Department of Environmental Engineering, INHA University, Incheon 22212, Korea.
Environ Sci Nano. 2023 Apr 21;10(7):1812-1827. doi: 10.1039/d2en01014c.
There is an increasing volume of nano-enabled materials in the market. Once composites containing nano-additives are disposed of, weathering could deteriorate their structures, releasing nanoparticles and risking exposure of humans and aquatic organisms. Composite degradation due to environmental aging continues, including structural deterioration resulting in cracking, fragmentation, and release of microplastics and nano-additives to the environment. This research aims to study the degradation and release of initially embedded nanomaterials (NMs) from composites and their toxicity. The molecular interaction of carbon nanotube (CNT)/polymer composites is critical for modifying the polymer properties. This study investigated the interactions of functional multiwalled carbon nanotube (MWCNT) composites which affect their release during accelerated weathering processes. Different epoxy-MWCNT composites were prepared by filling a polymer with pure MWCNTs and MWCNTs functionalized with acid () and amine () groups. The physical and chemical changes of aged composites were characterized by gravimetric analysis, contact angle measurements, FTIR, SEM, and laser confocal microscopy. A loss of hydrophobicity was observed for composite surfaces long before surface cracks materialized. Released polymer fragments and nanoparticles were analyzed in wash water using TEM, FTIR and Raman spectroscopy. The environmental risks for long-term use of CNT-polymer composites and the influence of fillers on the extent of chemical photodegradation depended on the combination of polymer and fillers. If nanoparticles are released from the matrix, the high surface-to-volume ratio and reactivity of NMs make them highly dynamic in environmental systems. Exposure to these released NMs could negatively affect human health and the environment. This study provides fragmentation and CNT particle release data that could describe how molecular-level interactions between functionalized CNTs and epoxy polymers affect the aging and release of CNTs. A toxicity assessment based on a reactive oxygen species (ROS) formation assay and MTS assay for cell viability and activity of the released polymer and CNT fragments and leachate showed moderate levels of cytotoxicity of released materials as compared to pristine epoxy plates.
市场上含纳米材料的产品数量日益增加。一旦含有纳米添加剂的复合材料被丢弃，风化作用可能会使其结构恶化，释放出纳米颗粒，从而使人类和水生生物面临暴露风险。由于环境老化导致的复合材料降解仍在持续，包括结构恶化，进而导致开裂、破碎，并向环境中释放微塑料和纳米添加剂。本研究旨在研究复合材料中初始嵌入的纳米材料（NMs）的降解与释放及其毒性。碳纳米管（CNT）/聚合物复合材料的分子相互作用对于改变聚合物性能至关重要。本研究调查了功能性多壁碳纳米管（MWCNT）复合材料在加速风化过程中的相互作用及其对释放的影响。通过将纯MWCNT以及用酸（）和胺（）基团功能化的MWCNT填充到聚合物中来制备不同的环氧-MWCNT复合材料。通过重量分析、接触角测量、傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）和激光共聚焦显微镜对老化复合材料的物理和化学变化进行表征。在表面裂纹出现之前很久，就观察到复合材料表面疏水性的丧失。使用透射电子显微镜（TEM）、FTIR和拉曼光谱对洗涤水中释放的聚合物碎片和纳米颗粒进行分析。CNT-聚合物复合材料长期使用的环境风险以及填料对化学光降解程度的影响取决于聚合物和填料的组合。如果纳米颗粒从基体中释放出来，纳米材料的高比表面积和高反应性使其在环境系统中具有高度的动态性。接触这些释放出的纳米材料可能会对人类健康和环境产生负面影响。本研究提供了破碎和CNT颗粒释放数据，这些数据可以描述功能化CNT与环氧聚合物之间的分子水平相互作用如何影响CNT的老化和释放。基于活性氧（ROS）形成测定以及用于评估释放的聚合物和CNT碎片及渗滤液的细胞活力和活性的MTS测定的毒性评估表明，与原始环氧板相比，释放材料的细胞毒性处于中等水平。
