Mass Spectrometry of Femto-Second Laser Photodegradation Products of Synthetic Polymers

Abstract

Femto-second laser photodegradations of polyethylene oxide (PEG), poly(ethylene oxide-b-propylene oxide) copolymer and polydimethylsiloxane (PDMS) were studied to investigate the degradation mechanism. MALDI-TOFMS and LC-APCI-MS were used for detail structural analysis of the degradation products. The results indicated that laser photodegradation proceeds within a few minutes in both aqueous and organic solutions. The degradation products of laser irradiation were identical to those of ultrasonic irradiation, but were not to those of thermal degradation in an aqueous solution using high-resolution mass spectrometry. Therefore, it is suggested that the mechanism of laser photodegradation of the polymers is due to the physical bond scissions through cavitation, just like ultrasonic degradation and the chemical reactions of the polymer chains with radicals formed from solvent or dissolved oxygen in laser-ablation.