Sun Tianlei, Song Runqiao, Balar Nrup, Sen Pratik, Kline R Joseph, O'Connor Brendan T
Department of Mechanical and Aerospace Engineering , North Carolina State University , Raleigh , North Carolina 27695 , United States.
Materials Science and Engineering Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States.
ACS Appl Mater Interfaces. 2019 Jan 23;11(3):3280-3289. doi: 10.1021/acsami.8b16457. Epub 2019 Jan 11.
Stretchable conductive polymer films are required to survive not only large tensile strain but also stay functional after the reduction in applied strain. In the deformation process, the elastomer substrate that is typically employed plays a critical role in response to the polymer film. In this study, we examine the role of a polydimethylsiloxane (PDMS) elastomer substrate on the ability to achieve stretchable PDPP-4T films. In particular, we consider the adhesion and near-surface modulus of the PDMS tuned through UV/ozone (UVO) treatment on the competition between film wrinkling and plastic deformation. We also consider the role of PDMS tension on the stability of films under cyclic strain. We find that increasing the near-surface modulus of the PDMS and maintaining the PDMS in tension throughout the cyclic strain process promote plastic deformation over film wrinkling. In addition, the UVO treatment increases film adhesion to the PDMS resulting in a significantly reduced film folding and delamination. For a 20 min UVO-treated PDMS, we show that a PDPP-4T film root-mean-square roughness is consistently below 3 nm for up to 100 strain cycles with a strain range of 40%. In addition, although the film is plastically deforming, the microstructural order is largely stable as probed by grazing incidence X-ray scattering and UV-visible spectroscopy. These results highlight the importance of neighboring elastomer characteristics on the ability to achieve stretchable polymer semiconductors.
可拉伸导电聚合物薄膜不仅需要承受大的拉伸应变，而且在施加应变降低后仍需保持功能。在变形过程中，通常使用的弹性体基材在响应聚合物薄膜方面起着关键作用。在本研究中，我们研究了聚二甲基硅氧烷（PDMS）弹性体基材对实现可拉伸PDPP - 4T薄膜能力的作用。特别是，我们考虑了通过紫外线/臭氧（UVO）处理调节的PDMS的附着力和近表面模量对薄膜起皱和塑性变形之间竞争的影响。我们还考虑了PDMS张力对循环应变下薄膜稳定性的作用。我们发现，增加PDMS的近表面模量并在整个循环应变过程中保持PDMS处于拉伸状态，会促进塑性变形而非薄膜起皱。此外，UVO处理增加了薄膜与PDMS的附着力，从而显著减少了薄膜的折叠和分层。对于经过20分钟UVO处理的PDMS，我们表明，在应变范围为40%的情况下，PDPP - 4T薄膜的均方根粗糙度在高达100个应变循环中始终低于3 nm。此外，尽管薄膜发生塑性变形，但通过掠入射X射线散射和紫外可见光谱探测发现，微观结构秩序在很大程度上是稳定的。这些结果突出了相邻弹性体特性对实现可拉伸聚合物半导体能力的重要性。
