Mirbagheri Marziye, Kaur Jasneet, Pham Hoang Vu, Adibnia Vahid, Zarrin Hadis, Banquy Xavier, Hwang Dae Kun
Department of Chemical Engineering, Faculty of Engineering & Architectural Science, Ryerson University, Toronto, Ontario M5B 2K3, Canada.
Keenan Research Center, Li Ki Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario M5B 1W8, Canada.
Langmuir. 2021 Jan 12;37(1):322-329. doi: 10.1021/acs.langmuir.0c02912. Epub 2020 Dec 21.
We report plasmon-free polymeric nanowrinkled substrates for surface-enhanced Raman spectroscopy (SERS). Our simple, rapid, and cost-effective fabrication method involves depositing a poly(ethylene glycol)diacrylate (PEGDA) prepolymer solution droplet on a fully polymerized, flat PEGDA substrate, followed by drying the droplet at room conditions and plasma treatment, which polymerizes the deposited layer. The thin polymer layer buckles under axial stress during plasma treatment due to its different mechanical properties from the underlying soft substrate, creating hierarchical wrinkled patterns. We demonstrate the variation of the wrinkling wavelength with the drying polymer molecular weight and concentration (direct relations are observed). A transition between micron to nanosized wrinkles is observed at 5 v % concentration of the lower molecular-weight polymer solution (PEGDA 250). The wrinkled substrates are observed to be reproducible, stable (at room conditions), and, especially, homogeneous at and below the transition regime, where nanowrinkles dominate, making them suitable candidates for SERS. As a proof-of-concept, the enhanced SERS performance of micro/nanowrinkled surfaces in detecting graphene and hexagonal boron nitride (h-BN) is illustrated. Compared to the SiO/Si surfaces, the wrinkled PEGDA substrates significantly enhanced the signature Raman band intensities of graphene and h-BN by a factor of 8 and 50, respectively.
我们报道了用于表面增强拉曼光谱（SERS）的无等离子体聚合物纳米皱纹基底。我们简单、快速且经济高效的制备方法包括将聚（乙二醇）二丙烯酸酯（PEGDA）预聚物溶液滴沉积在完全聚合的平坦PEGDA基底上，然后在室温条件下干燥液滴并进行等离子体处理，这会使沉积层聚合。由于其与下层柔软基底的机械性能不同，在等离子体处理过程中，薄聚合物层在轴向应力下会发生屈曲，从而产生分级皱纹图案。我们展示了皱纹波长随干燥聚合物分子量和浓度的变化（观察到直接关系）。在较低分子量聚合物溶液（PEGDA 250）浓度为5 v%时，观察到从微米级皱纹到纳米级皱纹的转变。观察到皱纹基底具有可重复性、稳定性（在室温条件下），特别是在纳米皱纹占主导的转变区域及以下区域具有均匀性，使其成为SERS的合适候选材料。作为概念验证，展示了微/纳米皱纹表面在检测石墨烯和六方氮化硼（h-BN）方面增强的SERS性能。与SiO/Si表面相比，皱纹PEGDA基底分别将石墨烯和h-BN的特征拉曼带强度显著提高了8倍和50倍。
