Effect of molecular weight on humidity-sensitive characteristics of electrospun polyethylene oxide

Abstract

Polymeric humidity sensors have been widely studied because of their advantages in terms of low cost, simple preparation, and easy process. Most of those researches focused on the improvement in the humidity sensing performance by adding other materials. However, it is also important to understand the correlation between the polymer property and sensing characteristics. In this study, polyethylene oxide (PEO) of various molecular weights was used for the humidity sensing material and prepared by electrospinning. The morphological change and electrochemical properties of the humidity active layer were investigated to demonstrate the effect of the molecular weight on the sensing performance, including the sensitivity and linearity of electrical impedance variation, response and recovery time, and moisture stability. The humidity sensor having the highest molecular weight presented the best sensitivity and linearity of the impedance change in the specific humidity range over 67% because it was composed of complete nanofibers and showed good electrochemical property. In addition, the fastest response and recovery time, least hysteresis, and excellent moisture stability were achieved by the high surface area and connectivity of the nanofibers.