Gaire Babu, Singla Saranshu, Dhinojwala Ali
School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325, USA.
Nanoscale. 2021 May 7;13(17):8098-8106. doi: 10.1039/d0nr08843a. Epub 2021 Apr 6.
A single layer of graphene when transferred to a solid substrate has the ability to screen or transmit interactions from the underlying substrate, which has direct consequences in applications of this 2D material to flexible electronics and sensors. Previous reports using a multitude of techniques present contradictory views on graphene's ability to screen or transmit van der Waals (vdW) and polar interactions. In the present study, we use interface-sensitive spectroscopy to demonstrate that a single layer graphene is opaque to hydrogen bonding interactions (a subset of acid-base interactions), answering a question that has remained unresolved for a decade. Similar frequency shifts of sapphire hydroxyl (OH) peak for graphene-coated sapphire in contact with air and polydimethylsiloxane (PDMS) demonstrate the insensitivity of sapphire OH to PDMS. The screening ability of graphene is also evident in the smaller magnitude of this frequency shift for graphene-coated sapphire in comparison to that for bare sapphire. The screening of acid-base interactions by a single layer graphene results in the significant reduction of adhesion hysteresis for PDMS lens on graphene-coated substrates (sapphire and silicon wafer, SiO/Si) than bare substrates. Our results have implications in the use of PDMS stamps to transfer graphene to other substrates eliminating the need for a wet-transfer process.
单层石墨烯转移到固体衬底上时，能够屏蔽或传递来自下层衬底的相互作用，这对这种二维材料在柔性电子学和传感器中的应用具有直接影响。以往使用多种技术的报告对石墨烯屏蔽或传递范德华（vdW）相互作用和极性相互作用的能力存在相互矛盾的观点。在本研究中，我们使用界面敏感光谱法证明单层石墨烯对氢键相互作用（酸碱相互作用的一个子集）是不透明的，从而回答了一个悬而未决十年的问题。与空气和聚二甲基硅氧烷（PDMS）接触的石墨烯包覆蓝宝石的蓝宝石羟基（OH）峰出现类似的频移，表明蓝宝石OH对PDMS不敏感。与裸蓝宝石相比，石墨烯包覆蓝宝石的这种频移幅度较小，这也证明了石墨烯的屏蔽能力。单层石墨烯对酸碱相互作用的屏蔽导致PDMS透镜在石墨烯包覆衬底（蓝宝石和硅片，SiO/Si）上的粘附滞后比裸衬底显著降低。我们的结果对于使用PDMS印章将石墨烯转移到其他衬底上具有启示意义，无需湿法转移过程。
