Effect of soft segments of waterborne polyurethane on organic vapor sensitivity of carbon black filled waterborne polyurethane composites

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.