Formation of polymer nanoparticles by UV pulsed laser ablation of poly(bisphenol A carbinate) in liquid environment

Abstract

Suspensions of poly(bisphenol A carbonate) (PBAC) nanoparticles of varying size and shape have been produced by ablation of a PBAC target with the fourth harmonic of a Q-switched Nd:YAG laser (wavelength 266 nm, pulses of 4 ns, repetition rate 10 Hz). The target was placed at the bottom of a rotating glass vessel filled with around a 10 mm column of liquid. The size distribution and shape of the obtained nanoparticles were characterized by atomic force microscopy (AFM) in dried drops of the suspension cast on a silicon (100) substrate. Laser ablation in water at fluences close to 1 J/cm2 leads to the generation of spherical particles with diameters of several tens of nanometers. Ablation at lower fluences, around 0.1 J/cm2, results in the production of nanoparticles of smaller diameters and also of non-spherical nanoparticles. Additional irradiations, at the fluence of 0.1 J/cm2, were performed in several liquid media with different properties in terms of density, viscosity, thermal conductivity and linear absorption coefficient at the laser ablation wavelength. Inspection of the obtained nanoparticles by AFM reveals differences in their shape and size as a function of the liquid used for irradiation. The different size distributions were related to the thermal conductivity of the systems, while viscosity of the liquids seems to be responsible for the development of the different morphologies