Development of a simultaneous LA-ICP-MS & LIBS method for the investigation of polymer degradation

Abstract

This work shows the development and optimization of simultaneous 193 nm LA-ICP-MS & LIBS methods for the spatially resolved analysis of polymer thin films of polyimide, polystyrene, and polyvinylpyrrolidone, which were exposed to a UV treatment and weathered in a corrosive atmosphere containing hydrogen sulfide, to investigate polymer ageing and degradation in harsh environments. Evaluating the information from a broadband multichannel LIBS instrument enabled the spatially resolved discrimination of the used polymer types with a lateral resolution of 40 μm. At the same time, a high-resolution spectrometer with an ICCD camera could detect oxidation derived from the UV treatment, and ICP-MS data could measure differences in the sulfur uptake derived from the sample film H2S weathering. In additional experiments, the depth resolution was optimized, depending on the polymer type to 150-360 nm, to gain information on the H2S diffusion profile and the sample depth affected by oxidation. Matrix-matched standards were used to calibrate the ICP-MS, enabling simultaneous determination of quantitative sulfur diffusion profiles and the influence of the UV treatment on the diffusion profiles. The capabilities of the combined measurement methods based on a 193 nm laser are well demonstrated on the differently treated polymer thin film samples used in this work, revealing spatially resolved information on different oxidation behavior, different sulfur diffusion profiles, and a significant decrease of the sulfur uptake in UV treated films - information that is not accessible with setups in previous literature.