Investigating the created microstructures and the induced changes in optical properties of PMMA by irradiation of a CO2 laser

Laser irradiation of polymers leads to the change of structural and optical properties. Because of its favorable features like cheapness and biocompatibility, poly (methyl methacrylate) (PMMA) is one of those polymers that is in widespread use in different areas such as manufacturing medial microfluidic devices. The aim of the present study is to investigate the effects of the pulse number and the above-threshold fluences of the CO2 laser in the creation of microstructures on the surface of PMMA polymer and variation of its optical properties, like absorption coefficient, refractive index, and bandgap energy. The obtained results indicate the formation of microstructures on the PMMA surface at the above-threshold fluences of the CO2 laser. At a fixed fluence, the density and width of the microstructures increase and decrease by increasing the number of incident pulses, respectively. By increasing the fluence at a fixed number of incident pulses the same trend forms in the microstructures. In the range of investigated fluences in this study, between 10-50 J/cm2, the width of the microstructures is measured to be between 10-15 micrometers. Consistent with previous experimental results, the results of this study indicate the enhancement of absorption coefficient, bandgap, and refractive index of the PMMA polymer after interaction with the CO2 laser.