Department of Chemical and Biomolecular Engineering , North Carolina State University , 911 Partners Way , Raleigh , North Carolina 27695 , United States.
Applied Sciences Group , Microsoft Corporation , Redmond 98052 , Washington , United States.
ACS Appl Mater Interfaces. 2018 Apr 4;10(13):11261-11268. doi: 10.1021/acsami.7b18394. Epub 2018 Mar 26.
This paper identifies and characterizes silicone elastomers that are well-suited for fabricating highly stretchable and tear-resistant devices that require interfacial bonding by plasma or UV ozone treatment. The ability to bond two or more pieces of molded silicone is important for creating microfluidic channels, chambers for pneumatically driven soft robotics, and other soft and stretchable devices. Sylgard-184 is a popular silicone, particularly for microfluidic applications. However, its low elongation at break (∼100% strain) and moderate tear strength (∼3 N/mm) make it unsuitable for emerging, mechanically demanding applications of silicone. In contrast, commercial silicones, such as Dragon Skin, have excellent mechanical properties yet are difficult to plasma-bond, likely because of the presence of silicone oils that soften the network yet migrate to the surface and interfere with plasma bonding. We found that extracting silicone oligomers from these soft networks allows these materials to bond but only when the Shore hardness exceeds a value of 15 A. It is also possible to mix highly stretchable silicones (Dragon Skin and Ecoflex) with Sylgard-184 to create silicones with intermediate mechanical properties; interestingly, these blends also only bond when the hardness exceeds 15 A. Eight different Pt-cured silicones were also screened; again, only those with Shore hardness above 15 A plasma-bond. The most promising silicones from this study are Sylgard-186 and Elastosil-M4130 and M4630, which exhibit a large deformation (>200% elongation at break), high tear strength (>12 N/mm), and strong plasma bonding. To illustrate the utility of these silicones, we created stretchable electrodes by injecting a liquid metal into microchannels created using such silicones, which may find use in soft robotics, electronic skin, and stretchable energy storage devices.
本文鉴定并描述了适用于制造高度可拉伸和抗撕裂器件的硅橡胶，这些器件需要通过等离子体或 UV 臭氧处理进行界面键合。将两块或更多块模制硅橡胶进行键合的能力对于创建微流道、气动驱动软机器人的腔室以及其他软质和可拉伸器件非常重要。Sylgard-184 是一种流行的硅橡胶，特别是在微流控应用中。然而，其断裂伸长率低（约 100%应变）和中等撕裂强度（约 3 N/mm）使其不适合新兴的对机械性能要求较高的硅橡胶应用。相比之下，商业硅橡胶，如 Dragon Skin，具有优异的机械性能，但难以进行等离子键合，这可能是由于存在硅氧烷油，它们会使网络软化，但会迁移到表面并干扰等离子键合。我们发现，从这些软网络中提取硅氧烷低聚物可以使这些材料键合，但只有当肖氏硬度超过 15A 时才可以。也可以将高可拉伸硅橡胶（Dragon Skin 和 Ecoflex）与 Sylgard-184 混合，以创建具有中间机械性能的硅橡胶；有趣的是，这些混合物也只有在硬度超过 15A 时才会键合。还筛选了八种不同的 Pt 固化硅橡胶；同样，只有肖氏硬度超过 15A 的硅橡胶才能进行等离子键合。从这项研究中最有前途的硅橡胶是 Sylgard-186 和 Elastosil-M4130 和 M4630，它们具有大变形（>200%断裂伸长率）、高撕裂强度（>12 N/mm）和强等离子键合。为了说明这些硅橡胶的实用性，我们通过将液态金属注入使用这些硅橡胶制成的微通道中，创建了可拉伸电极，这可能在软机器人、电子皮肤和可拉伸储能设备中得到应用。
