Surface Structuring of Poly(Methyl Methacrylate) by 1030-nm Femtosecond Laser Irradiation

Abstract The structure of the modified surface of poly(methyl methacrylate) (PMMA) after exposure to femtosecond (fs) laser radiation (wavelength 1033 nm, pulse duration 260 fs, repetition rate 1 kHz) was investigated by Fourier-transform infrared (FTIR) spectroscopy–microscopy in attenuated total reflection (ATR) mode, Raman spectroscopy–microscopy, scanning electron microscopy (SEM), and confocal fluorescence microscopy. The dependence of the surface structure and spectral characteristics of PMMA on the fs laser irradiation power was examined. Broadband luminescence with an anomalously large Stokes shift of approximately 5200 cm−1 was observed in the laser-treated region of PMMA. SEM images demonstrate an increase in surface roughness with increasing fs laser power. The FTIR and Raman spectra reveal an increase in the intensity of bands in the treated region of PMMA assigned to C=O vibrations in lactone and anhydride structures as the fs laser power increases. Principal component analysis of the Raman spectra identifies broad bands in the band G and D regions, attributed to highly disordered carbon.