Citation:

Sahle-Demessie, Endalkac, C. Han, E. Varughese, Brad Acrey, AND R. Zepp. Fragmentation and release of pristine and functionalized carbon nanotubes from epoxy-nanocomposites during accelerated weathering. Environmental Science: Nano. Royal Society of Chemistry, Cambridge, Uk, 10(7):1812-1827, (2023). https://doi.org/10.1039/D2EN01014C

Impact/Purpose:

Epoxy-based materials are widely used for coatings, electronics insulations, and waterproofing applications due to their excellent properties. Weathering of epoxy-and carbon nanotube (CNT) composites released phenolic and aromatic compounds, nanomaterials, and polymer fragments. CNT-epoxy degradation is not significantly influenced by the addition of functionalized CNT added. However, the functional modification of CNT could modulate the release properties of nano-additives. Epoxy added acid-functionalized CNT showed less free release than the non-functionalized and amine-functionalized CNT. The release material from neat epoxy and CNT-epoxy composite showed moderate cytotoxicity – based on ROS generation, cell activity, and viability tests. The toxicity appears more responsible due to organic components than released nanomaterials

Description:

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 (–COOH) and amine (–NH2) 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. 

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