A Novel Gas Sensor from Poly(ethylene glycol)-Grafted Carbon Black. Responsibility of Electric Resistance of Poly(ethylene glycol)- Grafted Carbon Black against Humidity and Solvent Vapor

Abstract

Poly(ethylene glycol) (PEG) having different molecular weight was successfully grafted onto carbon black surface by direct condensation of terminal hydroxyl groups of PEG with carboxyl groups on the surface using N,N'dicyclohexylcarbodiimide as a condensing agent. The electric resistance of a composite prepared from PEG and PEGgrafted carbon black drastically increased to 10 3-10 4 times of initial resistance in humidity and vapor of methanol, and ethanol, which are good solvent of PEG, and returned immediately to initial resistance when it was transferred in dry air. But the change of electric resistance of the composite was hardly observed in hexane and toluene vapor, which are poor solvent of PEG. The logarithm of electric resistance is linearly proportional to relative humidity. The sensitivity of electric resistance decreased with increasing molecular weight of PEG. In addition, the electric resistance of the composite from PEG-grafted carbon black lost the responsibility against solvent vapor above melting point of PEG. By crosslinking of the composite from PEG-grafted carbon black with triisocyanate, the responsibility against solvent vapor disappeared completely. These results indicated that the crystalline structure of PEG plays an important role on the responsibility of electric resistance of PEG-grafted carbon blacks against humidity and alcohol vapor.

Radiation Grafting of Polyethylene onto Conductive Carbon Black and Application as a Novel Gas Sensor

“…The details of the preparation for the sensor materials, measurements of electric resistance and response analysis are described in our previous papers. [4][5][6][7][8] …”

“…[4][5][6][7][8] Therefore, the radiation grafting onto carbon black is very effective to achieve the effective grafting onto carbon black having few functional groups, such as conductive carbon black.…”

“…[4][5][6][7][8] This makes the composite become a new potential gas sensor material. In this study, an initial exploring investigation was conducted to find the effects of PE-grafted carbon black on the electric resistance response of the composite as a gas sensor material.…”

“…als for a novel gas sensor. [4][5][6][7][8] In general, the conductive carbon black has no functional groups as grafting sites of a polymer. In previous studies, the grafting of PE onto conductive carbon black was achieved by the reaction of low molecular weight oxidized PE having hydroxyl groups with carboxyl groups on carbon black, which were previously introduced by the radical trapping method.…”

Novel Contamination and Gas Sensor Materials from Amphiphilic Polymer-Grafted Carbon Black

“…[5][6][7][8] On the other hand, Narkis et al 9 have reported the solvent sensing by use of conductive carbon black/polymer composite. Lews et al 10,11 and Zhang et al [12][13][14][15] have also reported the solvent vapor sensing behavior of carbon black/amorphous polymer composites.…”