Fabrication and Characterization of Carbon Nanotube/Poly(vinyl alcohol) Composites (original) (raw)
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Fabrication and characterization of carbon nanoparticles for polymer based vapor sensors
Sensors and Actuators B-chemical, 2004
The working principle of composite polymer vapor sensors is basically to exploit the vapor absorption properties of an insulating polymer whose electrical properties are modulated by a conductive "filler". Carbon black and graphite powder have already been used as "filler" materials [Sens. In this work we fabricate and characterize vapor sensors with a new type of "filler": carbon nanoparticles obtained by flame synthesis. Electrochemically prepared porous silicon with a 40% porosity has been used as the substrate for the carbon growth. Carbon nanoparticles have been characterized by AFM, SEM, FTIR; XRD, diffraction laser spectroscopy, nitrogen isothermal adsorption and visible optical micrography. The carbon structures seem composed of "units" whose size is in the range 5-20 nm. Composite thin films have been realized using mainly poly(methyl-methacrylate) (PMMA) as polymeric insulating matrix. Thin films of the composite are used to realize chemiresistor sensing devices. The characteristics of the sensors responses to volatile organic compounds (VOCs) are related to filler types in order to optimize the sensing device and show the importance of the filler characteristics.
Porous carbon nanotube/PMMA conductive composites as a sensitive layer in vapor sensors
Smart Materials & Structures, 2011
A novel vapor sensor was fabricated by multi-walled carbon nanotube (MWCNT) porous composite. Poly(methyl methacrylate) (PMMA) was used as a matrix. Porous sensing films were obtained by the dry-cast non-solvent-induced phase separation (NIPS) method. The experimental results showed a remarkable improvement in sensitivity and response time of conductive porous composite vapor sensors in comparison with dense composites. The response of porous films was about five times greater than dense ones with comparable thicknesses. In addition, the effect of surface modification of nanotubes on sensitivity of porous sensors was evaluated. It was observed that functionalized CNT/PMMA porous composite sensors show higher responsiveness towards a series of organic vapors. Their response was approximately ten times greater than the response of similar sensors without functionalization of CNTs, which was explained on the basis of polar interactions of vapors on the surface of CNTs and better dispersion of nanotubes in the polymer matrix.
Sensors and Actuators B: Chemical, 2011
Poly(vinyl alcohol) was modified by esterification to prepare poly(vinyl alcohol) copolymers. The degree of esterification on poly(vinyl alcohol) was elucidated by FTIR, 1 H NMR, and elemental analysis. The obtained products were poly(vinyl benzoate)-co-poly(vinyl alcohol) (B-PVA) and poly(vinyl p-toluoate)co-poly(vinyl alcohol) (P-PVA). The chemical vapor sensors were fabricated by the mixtures of polymer and carbon black in dimethyl sulfoxide and their subsequent preparation as thin films onto the interdigited electrodes by the application of the spin-coating technique. The chemical vapor sensing properties of the sensors were examined with various solvents, such as hexane, toluene, methanol, ethanol, isopropanol, tetrahydrofuran, ethyl acetate, acetonitrile, dimethyl sulfoxide, and water. The experimental results indicated that modifying the chemical structure of PVA results in the decreased polarity of the obtained products. The composites of modified PVA consequently responded well to low polarity solvents, such as THF or ethyl acetate.
Carbon nanomaterial polymer composite chemFET and chemoresistors for vapour sensing
Carbon nanotubes (CNTs) have been proposed for a broad spectrum of applications, including chemical sensing. Here we report on an investigation of multi-walled CNTs (MWCNTs) as conductive filler for composite polymer sensing films. Such materials combine conductive fillers with an insulating polymer to produce a chemically sensitive, electrically conducting material. These polymer composites offer several important advantages for chemical sensing, including room temperature operation (hence ultra low power), a broad range of selectivities (due to the wide choice of available polymers), and low manufacturing cost. Our approach is to compare the sensing qualities of these composite films, in resistive and field-effect configurations, with existing carbon black polymer composites. Their responses to propanol and toluene vapour in air show that the carbon black resistive sensors outperform CNT sensors by a factor of four in response magnitude. Thus we conclude that for these vapours and using this sensor fabrication method, carbon black polymer composite films are preferable for chemical sensing than MWCNT polymer composites.
Polycarbonate-carbon nanotubes transducers with hierarchical structure for vapor sensing
Combining multiwall carbon nanotubes (CNT) with an insulating polymer matrix provides a new promising generation of cost effective conductive polymer nanocomposites (CPC). CPC can be used to develop smart materials revealing changes of electrical properties upon external stresses such as heat, vapor or strain. In this work the development of conductive polymer nanocomposite (CPC) sensors for volatile organic compounds (VOC) detection has been carried out using a spray layer by layer process. This technique was successfully used to hierarchically structure polycarbonate-multiwall carbon nanotubes (PC-CNT) solutions into a double percolated architecture as attested by atomic force microscopy (AFM) and optical microscopy (OM). Chemo-electrical properties were investigated in the presence of different solvents at room temperature. Results have shown that vapor sensing properties of the obtained samples are related to different parameters such as filler content, vapor nature, thickness o...
Journal of Nanoscience and Nanotechnology, 2011
We investigate the chemical sensing behavior of composites prepared with polyvinyl alcohol and carbon materials (undoped multiwalled carbon nanotubes, nitrogen-doped multiwalled carbon nanotubes and carbon nanocoils). We determine the sensitivity of thin films of these composites for ethanol, methanol and toluene vapor, comparing their conductance and capacitance responses. The composite that exhibits highest sensitivity depends on specific vapor, vapor concentration and measured electrical response, showing that the interactivity of the carbon structure with chemical species depend on structural specificities of the carbon structure and doping.
Sensors and Actuators B: Chemical, 2009
The development of conductive polymer nanocomposite (CPC) sensors for volatile organic compounds (VOC) detection has been carried out using a spray layer by layer (LbL) process. This technique was successfully used to hierarchically structure polycarbonate-multiwall carbon nanotubes (PC-CNT) solutions into a double percolated architecture as attested by atomic force microscopy (AFM) and optical microscopy (OM). PC-CNT vapour sensing behaviour was investigated as a function of CNT content, films thickness, vapour flow and vapours solubility parameter. The response ranking A r (toluene) > A r (methanol) > A r (water) of PC-CNT was found to be coherent with 12 Flory-Huggins interaction parameters provided that signals are normalised by analyte molecules number. Signals shape was interpreted to the light of Langmuir-Henry-Clustering (LHC) model and found to be proportional to vapour content.
The investigation of sensing mechanism of ethanol vapour in polymer-nanostructured carbon composite
Central European Journal of Physics, 2010
Polymer-nanostructured carbon composites (PNCC) using three different polymers as composite matrix materials (polyvinylacetate (PVAc), polyethylene glycol (PEG) and ethylene-vinylacetate copolymer (EVA)) have been developed. High structure carbon black Printex XE2 (Degussa AG) was used as a composites filler. Ethanol vapour sensor-effect of composites was determined as a change of electrical resistance as the composite was held in ethanol vapour for 30 seconds. Reversibility of electrical resistance of PNCC, response stability and repeatability have been measured and compared. The electrical resistance response of EVA-nanostructured carbon composite (EVA-NCC) to ethanol vapour as a function of vinylacetate content in the copolymer has been evaluated. Promising ethanol vapour sensor-effect has been observed for PEG-NCC followed by PVAc-NCC and EVA-NCC.
Carbon nanotubes/poly(ε-caprolactone) composite vapour sensors
Carbon, 2009
The influence of carbon nanotube (CNT) grafting with poly(e-caprolactone) (PCL) on vapour sensing properties has been investigated for a series of Conductive Polymer Composite (CPC) transducers developed by layer by layer spray from PCL-CNT solutions. Grafting of e-caprolactone on the CNT surface through in situ ring opening polymerisation was demonstrated by nuclear magnetic resonance after solvent extraction of ungrafted chains.
Effect of Nanotube Aspect Ratio on Chemical Vapour Sensing Properties of Polymer/MWCNT Composites
Journal of Nano Research, 2012
The main topic of this paper is the study of polyisoprene-multi wall carbon nanotubes (PiMWCNT) composite's electrical conductivity and volatile organic compound sensing properties with respect to type of multi wall carbon nanotubes used. Electrical percolation parameters like percolation threshold and critical exponent of produced composites are determined and analyzed. PiMWCNT composites exhibit a promising sensitivity to the presence of volatile organic compounds. Therefore the composite's sensing mechanism of volatile organic compounds are analyzed in more detail by applying an original measuring technique which enables simultaneous measurement of an electrical resistance, mass and length change measurement of the sample in the presence and subsequent absence of a vapour. Measurement results enabled the evaluation of both vapour diffusion behavior in the composite and electrical resistance change mechanism.