Photoemission study of pristine and photodegraded poly(methyl methacrylate)

Degradation of poly(methyl methacrylate) (PMMA) thin films by vacuum ultraviolet (VUV) monochromatic synchrotron radiation was investigated by ultraviolet photoelectron spectroscopy. The photodegradation reaction was analyzed, for the first time, by different spectrometry techniques and ab initio molecular orbital calculations. It is concluded that the main degradation mechanism in PMMA by VUV photons is ascribed to the disappearance of ester groups and formation of double bonds in the polymer chain. The final product of the degradation seems to possess a relatively rich conjugation of unsaturated bonds. The rate constant of the degradation by VUV photons is evaluated to be 2.4×10-17 photons-1 cm2. © 1998 American Institute of Physics