Thermal decomposition/incineration of nano-enabled coatings and effects of nanofiller/matrix properties and operational conditions on byproduct release dynamics: Potential environmental health implications

Nano-enabled coatings (NECs) are a growing class of nanomaterials used in architectural applications that are likely to be thermally decomposed at their end-of-life via commercial waste incineration or accidental fires in buildings, thereby increasing concern over the potential release of engineered nanomaterials (ENMs) used as nanofillers. This is especially important for NECs as they have a larger surface-to-volume ratio compared to more traditional nano-enabled products (NEPs). In addition, questions remain about effects of nanofiller and NEC matrix properties and incineration operational conditions on NECs' thermal decomposition (TD) behavior and the physicochemical and morphological (PCM) properties of associated byproducts. In this study, the recently developed Integrated Exposure Generation System (INEXS) platform was used to identify important factors governing TD of NECs and assess potential environmental health implications. Findings confirm that nanofiller chemical composition, size and mass loading in the matrix, as well as incineration conditions, influence nanofiller release into the aerosol. Conversely, the morphology, mass-size distribution and the overall elemental and organic carbon content of the released aerosol are primarily governed by the host NEC matrix properties. The remaining residual ash properties are strongly dependent on the physicochemical composition of the nanofiller. Overall, the study highlights important byproduct release dynamics and exposure profiles during TD of NECs and warrants further studies on understanding the synergistic interactions between the released byproducts, their fate and transformations, and their toxicological and environmental health implications.