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UV-Laser Induced Structuring Of Polymer Surfaces

Excimerlaser induced ablation of polymers is often accompanied by a modification of the surface morphology at the irradiated regions. Only very recently models have been proposed for this effect, the origin being searched in different absorption properties of crystalline and amorphous material. A study of the authors on synthetic fibers irradiated by the uv-laser is in contrast with that assumption and gave evidence of a thermal contribution to laser-polymer-interaction. A strong influence of internal or external stress fields is found. On this basis a synergetic understanding of the surface structures is proposed. This model regards blocked stress fields, which are frozen in internally or applied externally, as the driving forces of self-organizing material convection, namely Marangoni-convection. These stress fields are thought to be released by the high temperatures and temperature gradients induced by the laser pulse.