Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.
Nanotechnology. 2012 Jun 1;23(21):215301. doi: 10.1088/0957-4484/23/21/215301. Epub 2012 May 3.
We investigate the nanometer-scale flow of molten polyethylene from a heated atomic force microscope (AFM) cantilever tip during thermal dip-pen nanolithography (tDPN). Polymer nanostructures were written for cantilever tip temperatures and substrate temperatures controlled over the range 100-260 °C and while the tip was either moving with speed 0.5-2.0 µm s(-1) or stationary and heated for 0.1-100 s. We find that polymer flow depends on surface capillary forces and not on shear between tip and substrate. The polymer mass flow rate is sensitive to the temperature-dependent polymer viscosity. The polymer flow is governed by thermal Marangoni forces and non-equilibrium wetting dynamics caused by a solidification front within the feature.
我们研究了在热浸式原子力显微镜（AFM）悬臂尖端进行热浸笔纳米光刻（tDPN）期间熔融聚乙烯的纳米级流动。聚合物纳米结构的写入是在悬臂尖端温度和基底温度控制在 100-260°C 范围内进行的，同时尖端以 0.5-2.0 µm s(-1)的速度移动或静止并加热 0.1-100 s。我们发现聚合物流动取决于表面毛细作用力，而不是尖端和基底之间的剪切力。聚合物的质量流速对依赖于温度的聚合物粘度敏感。聚合物的流动由热马兰戈尼力和由特征内的凝固前沿引起的非平衡润湿动力学控制。
