Abdulla Sukhananazerin, Pullithadathil Biji
Nanosensor Laboratory, PSG Institute of Advanced Studies, Coimbatore 641 004, India.
Department of Automobile Engineering, PSG College of Technology, Coimbatore 641 004, India.
Langmuir. 2020 Oct 6;36(39):11618-11628. doi: 10.1021/acs.langmuir.0c02200. Epub 2020 Sep 25.
Herein, we report the formation of well-aligned ultrathin films of polyaniline-functionalized multiwalled carbon nanotubes (PANI@MWCNTs) with a high orientational order over a macroscopic area by Langmuir-Blodgett (LB) technique and its enhanced ammonia gas sensing properties. During the interfacial assembly process, the PANI@MWCNTs gradually align to form small ordered blocks at the air-water interface, which further organize as a well-defined oriented monolayer. The orientation and alignment of PANI@MWCNTs in Langmuir films at the air-water interface were systematically studied as a function of interface temperature using transmission electron microscopic analysis. Surface functionalization of MWCNTs with polyaniline was found to overcome the 3D aggregation of CNTs leading to an oriented assembly of PANI@MWCNTs. The formation and stability of the compact monolayer/multilayer structures of PANI@MWCNTs-based LB films have been extensively studied using a π- isotherm analysis and thermodynamic approach. For the first time, such highly oriented LB films of PANI-functionalized MWCNTs have been employed for ammonia gas sensing applications at room temperature. The sensor was found to exhibit outstanding sensitivity toward NH at room temperature compared to random networks, which is attributed to the directed electron transport through the aligned PANI@MWCNTs. The ultrathin LB film allows fast analyte diffusion due to the adequate molecular accommodation in the oriented assembly of the active sensing layer. The large-scale alignment of PANI@MWCNTs demonstrated in this investigation would enable the fabrication of high-density MEMS (micro-electromechanical system)-based nanoscale sensor arrays for high-performance NH gas sensor applications.
在此，我们报道了通过朗缪尔-布洛杰特（LB）技术在宏观区域形成具有高取向有序性的聚苯胺功能化多壁碳纳米管（PANI@MWCNTs）的排列良好的超薄膜及其增强的氨气传感特性。在界面组装过程中，PANI@MWCNTs逐渐排列，在空气-水界面形成小的有序块，这些有序块进一步组织成定义明确的取向单层。使用透射电子显微镜分析系统地研究了空气-水界面处朗缪尔膜中PANI@MWCNTs的取向和排列与界面温度的关系。发现用聚苯胺对多壁碳纳米管进行表面功能化可克服碳纳米管的三维聚集，从而导致PANI@MWCNTs的取向组装。使用π等温线分析和热力学方法广泛研究了基于PANI@MWCNTs的LB膜的致密单层/多层结构的形成和稳定性。首次将这种高度取向的PANI功能化多壁碳纳米管LB膜用于室温下的氨气传感应用。与随机网络相比，该传感器在室温下对NH表现出出色的灵敏度，这归因于通过排列的PANI@MWCNTs的定向电子传输。由于活性传感层的取向组装中有足够的分子容纳空间，超薄LB膜允许分析物快速扩散。本研究中展示的PANI@MWCNTs的大规模排列将能够制造用于高性能NH气体传感器应用的基于高密度微机电系统（MEMS）的纳米级传感器阵列。
