Conducting Polymer nanoComposites (CPC): Nanocharacterisation of layer by layer sprayed PMMA-CNT vapour sensors by Atomi
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Conducting Polymer nanoComposites (CPC): Nanocharacterisation of layer by layer sprayed PMMA-CNT vapour sensors by Atomic force Microscopy in current Sensing Mode (CS-AFM) Bijandra KUMAR1, Mickaël CASTRO1, Jianbo LU1, Jean-François FELLER1 Materials Engineering Laboratory of Brittany (LIMATB), European University of Brittany (UEB), UBS-Lorient, France. ABSTRACT Organic vapour sensors based on poly (methylmethacrylate)-multi-wall carbon nanotubes (PMMA-CNT) conductive polymer nanocomposite (CPC) were developed via layer by layer technique by spray deposition. CPC Sensors were exposed to three different classes of solvents (chloroform, methanol and water) and their chemo-electrical properties were followed as a function of CNT content in dynamic mode. Detection time was found to be shorter than that necessary for full recovery of initial state. CNT real three dimensional networks have been visualized by Atomic force microscopy in a field assisted intermittent contact mode. More interestingly real conductive network system and electrical ability of CPC have been explored by current-sensing atomic force microscopy (CS-AFM). Realistic effect of voltage on electrical conductivity has been found linear.
INTRODUCTION Carbon nanotubes (CNT) based materials have explored a new generation of smart materials due to its unique electronic and mechanical properties [1]. Electronic properties of CNT are very sensitive to the surrounding environments [2- 3]. This characteristic of carbon nanotubes makes them extremely attractive and suitable for sensors design. Basically electrically conductive paths, which are generally achieved through the dispersion of carbon or metal nanofillers into an insulating polymer matrix is the primary condition to prepare conducting polymer nanocomposites (CPC). Among different techniques, Layer-by-Layer (LbL) assembly approach is found to be a very efficient method to prepare well dispersed multilayer films of CNT based CPC. The specific nature of the LbL films allows the interactions between the components to be maximized [4]. CPC are widely used for sensing as smart materials. [5,-7] Furthermore, much less attention is paid to the real characterization of CPC structure at the nanoscale while local electrical properties of CPC are almost no studied in-situ during the sensing experiments because of instruments limitation of It is especially true with transmission electron microscopy (TEM) which is the most common high resolution microscopic technique for morphological studies of embedded nanofillers, such as CNT, within polymer matrices. Nevertheless, other techniques, such as scanning near-field optical microscopy (SNOM), are successfully used. However, most of these techniques require tedious sample preparation and special instrumental modification [8] Alternatively, atomic force microscopy (AFM) has shown promises to study the electrical properties of materials with high resolution even at the nanometre scale. After required
modifications it can give a variety of otherwise impossibl
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