Gas sensing conductive composites capable of size-dependent molecular discrimination and screening

The present work developed carbon-black-filled waterborne polyurethane composites, in which cyclodextrins acted as the hard segments. The composites proved to be accompanied by selective gas sensitivity. Upon exposure to certain organic solvent vapors, electrical resistance of the composites drastically increased. The maximum magnitude of resistance variation was found to be a function of the molecular size of the analyte. Besides, the composites containing different cyclodextrins exhibit different maximum responsivity against identical gaseous analytes. According to these characteristics, molecular discrimination and screening, which used to be conducted by expensive analytical instruments, might be done simply by examining the resistance change in an analyte's vapor. It was found that selective adsorption on cyclodextrins should be responsible for the specific response habit of the composites.