通过合理选择聚合物分子结构模型和高精度势能函数,建立了聚合物飞秒激光烧蚀加工的分子动力学仿真模型,并使用该模型研究了聚乙烯和聚苯乙烯飞秒激光烧蚀加工中的激光能量辐照和扩散过程。研究结果表明: 激光烧蚀加工中聚合物材料的去除方式包括单链热激发引起的表面蒸发和单链热运动引起的内部热膨胀。聚苯乙烯单链的微观变形方式包括单链的整体移动和单链自身结构的变化。聚乙烯和聚苯乙烯的分子结构差异对聚合物单链变形行为和材料去除体积等烧蚀加工结果具有显著的影响。

To improve the machining accuracy of the hole on the polystyrene microspheres for laser fusion, a fundamental understanding of the mechanisms of femtosecond laser ablation is required. We establish a molecular dynamics model of femtosecond laser ablation of polymers by optimally selecting the molecule representation model and related force field. Subsequent molecular dynamics simulations of femtosecond laser ablation of polyethylene and polystyrene show that the laser ablation-induced polymer material removal is caused by single chain ejection-accompanied surface evaporation and single chain motion-accompanied thermal expansion within the bulk. Furthermore, the microscopic deformation mechanisms of the single chain include inter-chain sliding and intra-chain change. It is found that the discrepancy in the molecule architecture has strong influence on the femtosecond laser ablation of polyethylene and polystyrene.