Development of solution processible organic-inorganic hybrid materials with core-shell framework for humidity monitoring

A novel organic-inorganic hybrid material with the core-shell framework was prepared by modifying the poly(vinylsulfonic acid, sodium salt) (PSS) on vinyl functionalized silica nanoparticles (VSNs) via the free radical polymerization. SNs with different contents of PSS were prepared and the structures were carefully characterized. The hybrid material could enhance the durability of PSS under high humidity environment. Meanwhile, the SNs skeleton provides interstitial channels in the PSS@SNs films, which are available for water molecules transport. The PSS coated SNs (PSS@SNs) films were formed by drop-coating and their sensing properties were investigated. The impedance of the optimal humidity sensor changed more than four orders of magnitude over the relative humidity range of 33-95%, with good linearity under semi-logarithm scale (R2 = 0.950) and a small humidity hysteresis of 2% RH. The obtained sensor also showed rapid response to humidity change (the response and recovery time were 2 and 65 s, respectively). Finally, the resultant sensor was explored for respiratory rate monitoring.