Electrical resistance response of carbon black filled amorphous polymer composite sensors to organic vapors at low vapor concentrations

Dong, Xian‐Zhe; Fu, Ruo Wen; Zhang, Ming Qiu; Zhang, Bin; Rong, Min Zhi

doi:10.1016/j.carbon.2004.05.034

Cited by 91 publications

(52 citation statements)

References 24 publications

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“…Most of the polymer sensors operation mechanism is explained by the solubility parameter [54][55][56][57][58]. The sorption of analyte vapor will induce swelling of the polymer and this affects the electron density on the polymer chain [59].…”

Section: Sensor Response Characteristics Conjugated Molecule Sensorsmentioning

confidence: 99%

Organic Molecule Based Sensor for Aldehyde Detection

Mallya

Ramamurthy

2015

Smart Sensors, Measurement and Instrumentation

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Abstract. Aldehydes are used in food and beverage industries, production of resins, soap and perfume industries. When used in excess quantity or found in products in undesired quantity this is a threat to humans. Hence it becomes very important to detect these VOCs even at lower concentration. The other sources of aldehyde are polluted air and water. Exposure to aldehyde can cause gene mutation and cancer. Conductometric sensors with metal oxide semiconductors as sensing films, cataluminesence based sensors, quartz crystal microbalance sensors, analytical methods such as HPLC have been used for the detection of aldehydes. These are sophisticated techniques require skilled staff to perform the tests. Chemiresistor is a simple method of fabrication of conductometric sensor. In this method the sensing layer is a film cast between two electrodes deposited on an insulating substrate. The response of the sensor to various analytes is monitored by recording the changes taking place in the sensing element. Organic molecule based sensors are low cost and operate at room temperature. Selectivity of the sensors to a particular analyte is an issue in sensors. An analyte molecule can interact with the various binding sites on a molecule. A molecule has to be designed and synthesized to be selective to a particular analyte of interest. This can be achieved by selecting a molecule which has a functional group that interacts with the analyte molecule. The mechanism of interaction of the analyte with the sensing molecule can be understood by doing molecular simulations. Molecular modelling allows monitoring the interaction of the analyte and sensing molecule. Here an example of organic molecule based sensor for selective interaction with aldehydes is illustrated.The organic molecule ophenylenediamine blended with carbon black as sensing element of the chemiresistor to decrease the resistance. Molecular modelling can be used to understand the interaction between aldehyde and o-phenylenediamine molecule.

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Section: Sensor Response Characteristics Conjugated Molecule Sensorsmentioning

confidence: 99%

Organic Molecule Based Sensor for Aldehyde Detection

Mallya

Ramamurthy

2015

Smart Sensors, Measurement and Instrumentation

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“…When the sensor was exposed to a solvent vapor, swelling of the polymer matrix decreases the electrical connectivity between the conductive particles within the composite, and cause an increase in electrical resistance [18,19]. For crystalline polymers, it was also considered that the polymer matrix within the composite is dissolved by solvent absorption, and the movement of carbon black particles in the amorphous regions causes the destruction of conductive networks, which results in the increase in electrical resistance consequently [13,14]. In some cases, the decreasing of resistance has been observed for polar solvent vapors due to the increasing the mobility of polar analytes, ionizable hydrophilic functional groups and/or doped ions in the sensing material if the hydrophilic polymers, polyelectrolytes and ion doped conductive polymers are used as sensing element [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

A STUDY on the sensitivity and selectivity properties of Polymer based gas-vapor sensors

Cankurtaran

Yazıcı

Karaman³

2016

J. Turk. Chem. Soc., Sect. A: Chem.

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Abstract:In this study, the water soluble poly (diphenylaminesulfonic acid) (PSDA) and the diblock copolymer of PSDA with poly(ethylene glycol) (PEG) were used to construct the interdigitated film electrodes (IDEs). Their responses against humidity and various solvent vapors were investigated by impedance measurements. Sorption and desorption behaviors of the solvents were determined by simultaneous registration of the impedance (Z) and the resistive (R, resistance) and capacitive (X, reactance) components of the Z under different potential bias and alternating current (ac) frequencies. The sensor responses were discussed considering the polar/non-polar and polarizability properties of the polymers and solvents. The effect of ac frequency and potential bias on the sensitivity and selectivity of the sensors were discussed. It was found that the solvent polarity is the primary effect on the electrical conductance and capacitance of both PSDA homopolymer and PSDA-b-PEG block copolymer. The results supported that the dipolarity-polarizability properties of solvents have also a critical role on sensor response at low ac frequencies. The more polarizable solvents gave higher sensor responses at lower ac frequencies. The equilibrium response of the PSDA based sensor was correlated with the dielectric constant of the solvents. The values of Z and R of PSDA film under saturated solvent vapors at 1 kHz ac frequency were linearly correlated (R 2 was 0.955, 0.993 and 0.957 for Z, R and X, respectively, in semi-logarithmic scale) with the values of the dielectric constants of the solvents, except water. A similar correlation (R 2 = 0.996) was obtained by using the R values of the PSDA film at 100 kHz ac frequency. In the case of PSDA-b-PEG polymer film, it was also possible to establish an almost linear correlation (R 2 =0.943) between the R at 100 kHz ac frequency and the values of the dielectric constants of the solvents, except acetone and water. Consequently, it was found that the applied ac frequency was distinctive on both the sensitivity and selectivity of the studied sensor.

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“…In addition, introduction of different soft segments into the molecules of the matrix polymer results in different responsivity even in the case of identical solvent vapor. In fact, magnitude of resistance change of a composite in response to organic vapor is determined not only by the amount of adsorbed solvent, 15,16 but also by the interaction between the adsorbed solvent molecules and the composite. 13 When CB loading in the composites is relatively low (4 wt % in the present CB/WPU, for example), adsorption of solvent gases of the composites has to be mainly controlled by the matrix polymer.…”

Section: Solvent-polymer Interactionmentioning

confidence: 99%

“…13 When CB loading in the composites is relatively low (4 wt % in the present CB/WPU, for example), adsorption of solvent gases of the composites has to be mainly controlled by the matrix polymer. 13,16 Therefore, the interaction between the adsorbed solvent molecules and the composites can be represented by the interaction between the adsorbed solvent molecules and the chain segments of matrix polymer, regardless of the contribution of CB.…”

Section: Solvent-polymer Interactionmentioning

confidence: 99%

Effect of Soft Segments of Waterborne Polyurethane on Organic Vapor Sensitivity of Carbon Black Filled Waterborne Polyurethane Composites

Zhao¹,

Fu²,

Zhang³

et al. 2006

Polym J

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ABSTRACT:In the present work, three types of waterborne polyurethane (WPU) were synthesized, in which poly(ethylene oxalate glycol), poly(propylene oxide) and poly(tetramethylene ether glycol) acted as the soft segments, respectively. The WPUs were then compounded with carbon black (CB) to fabricate gas sensing composites. By studying the composites' resistance variation in different solvent-vapors, it was found that the structures of the WPUs remarkably affected the composites' response behaviors. Both polarity and flexibility of the soft segments of WPU determine to a great extent the solvent-polymer interaction and preferential localization of solvent and fillers, resulting in different magnitudes of resistance increase and rates of response. Recently carbon black (CB) filled polymer composites have been exploited for the fabrication of chemical sensors.1,2 When being exposed to organic vapors, the composites exhibit a drastic increase in their electrical resistivity because matrix swelling induced by solvents absorption expands the inter-filler gap.3,4 Removal of the stimuli leads to desorption of the vapors and a decrease in the composites' resistance back to the original value. On the basis of this feature, therefore, low cost organic solvent leak detectors and ''electronic noses'' can be manufactured. [5][6][7] In the authors' lab, waterborne polyurethane (WPU) was employed to be mixed with CB for preparing gas sensing composites.8 As WPU is a segmented polymer consisting of the alternating sequence of long non-polar soft segments and short polar hard segments that constitute a unique microphase separation structure, its composites with CB exhibit widespectrum responsivity to both low/non-polar and polar solvents. [9][10][11][12] It was found that the segmented microstructure of WPU greatly influenced the relationships between solvent adsorption behavior and electrical resistance variation of WPU based composites. 13In this context, it is worth studying the effect of soft segments on vapor sensitivity of CB/WPU composites, which might lead to optimization of the polymer's microstructure and hence the sensing performance of the composites. Accordingly, three kinds of WPU were synthesized in the present work, in which only the soft segments are different. These soft segments were selected because of their distinct structures and features. As shown in Table I, poly(tetramethylene ether glycol) (PTMEG) possesses the highest flexibility because there is no side groups on its skeleton, while poly(ethylene oxalate glycol) (PEOG) has the lowest flexibility due to the strong interaction between the ester groups. In regard to polarity, however, the above rank has to be reversed. By comparing electrical response habits of the composites based on these WPUs in benzene (non-polar solvent), chloroform (low polar solvent) and acetone (polar solvent) vapors, it is believed that the influence of WPU microstructure on composites sensitivity would be revealed. EXPERIMENTAL MaterialsAnalytically pure ethylenediamine anhydrou...

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Electrical resistance response of carbon black filled amorphous polymer composite sensors to organic vapors at low vapor concentrations

Cited by 91 publications

References 24 publications

Organic Molecule Based Sensor for Aldehyde Detection

Organic Molecule Based Sensor for Aldehyde Detection

A STUDY on the sensitivity and selectivity properties of Polymer based gas-vapor sensors

Effect of Soft Segments of Waterborne Polyurethane on Organic Vapor Sensitivity of Carbon Black Filled Waterborne Polyurethane Composites

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