Nano-Sized Polyethylene Particles Produced by Nano-Second UV Laser Ablation

Model samples of nano-sized crystalline plastics (NPs), which are useful for the study of interactions with biological systems and toxicity studies, were artificially prepared by laser ablation. Nano-sized particles were synthesized by irradiating a 50 μm thick Low-density Polyethylene (LDPE) film with ultraviolet (266 nm) nano-second laser beams at an irradiation fluence of 40 mJ/cm², a beam area of 0.023 cm² and a repetition rate of 10 Hz to locally break the σ bonds. The LDPE film was placed in a cell filled with ultra-pure water in an environment as free as possible from solvent residues and surfactants. The particles generated by nano-second laser ablation were evaluated by a DLS particle size, zeta potential, and molecular weight measurement system. The shape of the nanoparticles was also confirmed by field emission scanning electron microscopy (FE-SEM). The particle size measurement by DLS confirmed the formation of 180–800 nm particles after 0.5–12 h of laser irradiation. The observation of the particle shape by FE-SEM showed not only independent particles, but also some agglomerated states. The application of laser ablation is shown to be an effective method for the generation of nano-sized plastic particles which can serve as model samples for ecological interactions and toxicity studies.