Organic solvent assisted laser processing of transparent polymer films based on the swelling and penetration behavior

Abstract

The laser processing of polymer films has significant importance due to the wide applications in various fields. The problems in laser processing of transparent polymer films caused by the poor absorption and current doping methods have prevailed. In this paper, a simple, efficient, and low-cost doping and laser processing method based on polymers’ swelling and penetration behavior was applied to improve the laser processing of transparent polymer films: organic solvent assisted laser processing (SALP). In the SALP method, various common organic solvent molecules (Ethanol, Acetone, N, N-dimethylformamide, Chloroform) were introduced into transparent polydimethylsiloxane (PDMS) films through the swelling and penetration (SP) pretreatment and acted as the dopant to improve the efficiency, capability, and quality of laser processing. Experimental results showed that the SALP method performed higher efficiency and capability (kerf depth: 296.79 ± 11.98 μm, kerf width: 16.59 ± 1.46 μm, kerf aspect ratio: 18.02 ± 1.98) under the same processing conditions compared to the typical laser processing (TLP) method (kerf depth: 137.36 ± 6.47 μm, kerf width: 27.30 ± 1.11 μm, kerf aspect ratio: 5.04 ± 0.31). The roughness of the kerf inner surface and the debris and microcracks on the kerf surface were also significantly reduced. More importantly, this method hardly influenced the original properties of the native polymer films due to the removability of organic solvents. On the one hand, the introduction of organic solvent molecules improved the optical absorption of PDMS films and the heat transfer during laser processing. On the other hand, the excitation, ionization, and dissociation of organic solvent molecules under laser irradiation improved the decomposition process of PDMS, which improved photochemical reaction and promoted the complete and uniform decomposition in laser processing. The SALP method has enlightening significance for improving the laser processing of polymers and investigating the laser ablation mechanism.