Facile preparation of N-rich functional polymer with porous framework as QCM sensing material for rapid humidity detection

Although many humidity sensing materials have satisfactory properties based on quartz crystal microbalance (QCM) transducer, their synthesis processes are complex. Herein, we report an effective and facile method to modify porous polypropylene microfiltration membrane (PPMM) evenly via the deposition of N-rich functional polymer (PDA-PEI), which was easily synthesized by crosslinking polydopamine (PDA) and polyethyleneimine (PEI). The PDA-PEI modified PPMM well retained the pore structure and was first employed to detect relative humidity based on QCM featured with rapid response, satisfactory repeatability and stability. Compared with PDA modified PPMM, the humidity sensing performance of PDA-PEI modified PPMM is improved considerably. Furthermore, the sensing mechanism study based on Gaussian 09 software reveals that the interaction between PDA-PEI and water molecules belongs to weak chemical adsorption. Such a comprehensive research foresees the potential application of PDA-PEI modified PPMM for fast detection of humidity indoor and outdoor.