Dynamics of Liquid Transfer from Nanoporous Stamps in High-Resolution Flexographic Printing
Dynamics of Liquid Transfer from Nanoporous Stamps in High-Resolution Flexographic Printing
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高分辨率柔版印刷中纳米孔印模的液体转移动力学
DOI：
10.1021/acs.langmuir.9b00460
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发表时间：
2019
期刊：
影响因子：
3.9
通讯作者：
Brun, Pierre-Thomas
中科院分区：
文献类型：
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作者：
Mariappan, Dhanushkodi D.;Kim, Sanha;Boutilier, Michael S.;Zhao, Junjie;Zhao, Hangbo;Beroz, Justin;Muecke, Ulrich;Sojoudi, Hossein;Gleason, Karen;Brun, Pierre-Thomas
印刷超薄层聚合物和胶体油墨对于在纸张和聚合物薄膜等非传统基材上制造电子产品至关重要。最近，我们发现纳米多孔邮票克服了传统聚合物邮票在柔版印刷中的关键局限性，即能够以微米级的横向精度印刷超薄纳米颗粒薄膜。在这里，我们研究了纳米多孔邮票和固体衬底之间的液体转移动力学。邮票由聚合物涂层的碳纳米管组成，邮票的表面力学和润湿性被设计成吸收胶体墨水，并在与目标基材接触时转移墨水。在印刷过程中，通过高速成像，我们观察了液体的扩散动力学，这是由纳米结构的印花表面之间的渐进接触和印花-衬底间隙内的基材和吸胀所介导的。从最终接触面积来看，油墨的转移量是由毛细管桥的破裂介导的；并且，破裂后，液体扩散以高精度填充由与印章几何形状匹配的前驱体膜定义的区域。通过流体动力学建模，并与数据比较，我们阐明了该过程的规模和速率限制方面。具体来说，我们发现印刷油墨体积和产生的层厚度与接触压力无关；打印层厚度随缩回速度的增加而减小。在这些条件下，厚度控制在<100纳米范围内的纳米颗粒薄膜可以用纳米多孔邮票柔印技术印刷，速度与工业印刷设备相当。
Printing of ultrathin layers of polymeric and colloidal inks is critical for the manufacturing of electronics on nonconventional substrates such as paper and polymer films. Recently, we found that nanoporous stamps overcome key limitations of traditional polymer stamps in flexographic printing, namely, enabling the printing of ultrathin nanoparticle films with micron-scale lateral precision. Here, we study the dynamics of liquid transfer between nanoporous stamps and solid substrates. The stamps comprise forests of polymer-coated carbon nanotubes, and the surface mechanics and wettability of the stamps are engineered to imbibe colloidal inks and transfer the ink upon contact with the target substrate. By high-speed imaging during printing, we observe the dynamics of liquid spreading, which is mediated by progressing contact between the nanostructured stamp surface and by the substrate and imbibition within the stamp–substrate gap. From the final contact area, the volume of ink transfer is mediated by rupture of a capillary bridge; and, after rupture, liquid spreads to fill the area defined by a precursor film matching the stamp geometry with high precision. Via modeling of the liquid dynamics, and comparison with data, we elucidate the scale- and rate-limiting aspects of the process. Specifically, we find that the printed ink volume and resulting layer thickness are independent of contact pressure; and that printed layer thickness decreases with retraction speed. Under these conditions, nanoparticle films with controlled thickness in the <100 nm regime can be printed using nanoporous stamp flexography, at speeds commensurate with industrial printing equipment.