Abstract

Polyethylene terephthalate (PET) microplastics and nanoplastics are ubiquitously present in the atmosphere as atmospheric and airborne forms (PET-aMPs). Using first-principles calculations, we analyze the uptake of primary air pollutants onto PET-aMPs, focusing on their stabilities, adsorption mechanisms, and thermochemistry. The results show that PET-aMPs are selective for the spontaneous adsorption of CO, CO2, NO, N2O, NO2, NH3, and SO2, reaching stable adsorption energies of 6-20 kcal/mol per molecule, with comparable uptake ability than carbon-based materials, metals/metalloids, and metal oxide surfaces. Then, PET-aMPs become a vector for coexisting air pollutants in the atmosphere, which adsorb by inner or outer adsorption depending on the mo-lecular polarity (dipole moment) and atomic constitution (electronegativity) of gaseous molecules. Also, atmo-spheric H2O and O-2 are not competitive molecules, and ozone could enhance adsorption due to surface oxidation and structure breakdown. The interplay of electrostatic (46-61%) and dispersion forces (21-58%) drives the adsorption mechanism, where low-polar pollutants display almost a balanced electrostatic vs. dispersion contribution, while high polar molecules display a higher electrostatic stabilization. The outer adsorption is reached by strong dispersion, hydrogen bonding, and dipole-dipole-induced pairs, while lone-pair-t interactions appear in the inner adsorption regime. These results expand the understanding of the hazards and risks of at-mospheric and airborne microplastics/nanoplastics, their impacts, co-transport ability, and interaction with the environment.