Nanoparticle polymer composite applications and environmental impacts

nanoparticle;polymer composite;nanocomposite;carbon nanotube;hollow fiber ultrafiltration membrane;quantum dot;artificial accelerated weathering;nanoparticle detection;Chemistry

Gallagher, Miranda JaneFairbrother, D. Howard ;

Johns Hopkins University

关键词: nanoparticle;    polymer composite;    nanocomposite;    carbon nanotube;    hollow fiber ultrafiltration membrane;    quantum dot;    artificial accelerated weathering;    nanoparticle detection;    Chemistry;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/60054/GALLAGHER-DISSERTATION-2018.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

The polymer composite field has significantly benefited from the inclusion of nanoparticles (NP) that impart size-dependent properties. In water filtration, containment removal and fouling rate are improved when available surface area is augmented with carbon nanotube (CNT) functionalization. Unfortunately, hydraulically unstable CNTs from flat sheet membrane designs are released into the waste stream of a drinking water plant. Efficient and sharp emission is achieved when LEDs are functionalized with quantum dots (QDs) films. Recognizing high turnover in electronics use, these ephemeral QLEDs, however, contain nanoparticles and metals of known ecological toxicity and unknown forms of release. The question remains: Do the benefits of implementing novel polymer nanocomposites outweigh the environmental impacts?With the goal of zero NP release during cleaning and backwashing, a hydraulically stable, ring-strained CNT active layer was developed on the inside surface of a hollow fiber membrane. The CNT active layer was resistant to backwashing, hydraulic stress, and cleaners as determined with scanning electron microscopy. Moreover, <1% mass loss was quantified with UV-Vis. Finally, compared to virgin membranes, CNT-modified membranes had improved fouling resistance through multiple cycles of filtration with a a bacteria surrogate.QD polymer composites were synthesized of either CdSe or CdSe/ZnS QDs in poly (methyl methacrylate) (PMMA). Nanoparticle release at QD-PMMA end-of-life was simulated by accelerated artificial weathering PMMA, CdSe-PMMA and CdSe/ZnS- PMMA with far-ultraviolet light. A comprehensive chemical characterization of weathered substrates and released fragments was undertaken. The transformed state of the components, QD containing PMMA fragments and ions, were detected with hyperspectral imaging, confocal laser scanning microscopy and inductively coupled mass spectrometry. A model organism, S. oneidensis MR-1 was exposed to the released fragments, which proved to be toxic in the most degraded CdSe-PMMA and CdSe/ZnS- PMMA fragments at ~40 μg/L [Cd]ttl. Notably, S. oneidensis Cd2+ tolerance was significantly higher at 200 μg/L. Thus, toxicity was not entirely caused by Cd2+.From these studies, two sustainable design considerations are suggested: i) develop structures that decrease the release of nanomaterials from polymers and ii) determine the released form of the polymer nanocomposite and assess toxicity to model organisms for all vested interests.