Context <p>Plastics can remain unchanged for long periods of time, thus generating large amounts of waste. Due to mechanical or chemical processes, plastics can be broken down into micro- and nanoplastics. To analyze the oxidative stress that nanoplastics might produce, 21 oligomers of polyhydroxyalkanoates (PHA) are investigated. We used oligomers of PHA as models of nanoplastics. We determined the electron donor–acceptor capacity using the Full Electron Donor–Acceptor Map described previously. All the investigated PHA exhibit the same electron donor and acceptor properties, regardless of the system size. They are all the worst electron donors and acceptors of the systems under consideration. These results indicate that these nanoplastics are not capable of electron transfer and, therefore, it is not evident that they can contribute to oxidative stress in animals and plants. The interaction of PHA with phloretin was also analyzed, since PHA is functionalized with phloretin to obtain packaging materials. The electron transfer capacity of PHA is enhanced in the presence of phloretin. This research suggests that PHA nanoplastics do not produce oxidative stress, which is important for further studies that are still required.</p> Methods <p>All DFT computations were performed using the Gaussian16 at def2-TZVP/ω-B97XD level of theory without symmetry constraints.</p>