A novel contamination sensor in solution: the response of the electric resistance of a composite based on crystalline polymer-grafted carbon black

The response of the electric resistance of the composite prepared from crystalline polymer-grafted carbon black as a function of the contamination in solution was investigated. The electric resistance of the composite prepared from poly(ε-caprolactone) (PCL)-grafted carbon black drastically increased in hexane, containing chloroform, trichloroethane, and ethanol and returned immediately to the initial resistance when it was transferred into pure hexane. The response of the electric resistance was highly reproducible. The logarithm of electric resistance was linearly proportional to the concentration of chloroform in hexane. Furthermore, the electric resistance of the composite prepared from crystalline poly(ethylene glycol) (PEG)-grafted and poly(ethylene adipate) (PEA)-grafted carbon black also drastically increased in hexane containing alcohol, which is a good solvent of the grafted chain (PEG and PEA). This is due to a widening of the gaps between the carbon black particles based on the absorption of solvent for these crystalline polymers.