Novel humidity sensitive materials derived from naphthalene-based poly (arylene ether ketone) containing sulfobutyl pendant groups

A series of novel side-chain-type sulfonated polymer aromatic electrolytes (PAEK-SO3Na-x) with different sulfonation degrees (Ds) were synthesized through a polycondensation of 1,5-bis(4-fluorobenzoyl)-2,6-dimethoxynaphthalene and hydroquinone, followed by a demethylation and sulfobutylation reaction. The structures and Ds of the polymers were confirmed by their 1H NMR spectra and the hydrophilic nature of the membranes was characterized by water uptake and contact angle test. A dual-mode sorption model was applied to analyze the water vapor sorption of the polymers. Humidity sensors were prepared from PAEK-SO3Na-x. Then the sensitivity and responsibility of the sensors were characterized in detail. The variation range of the impedance of the sensors was from 107 Ω to 102 Ω between 11% RH and 97% RH, which was wider than many other polymeric humidity sensors reported and indicated a good sensitivity. The response time of PAEK-SO3Na-80 was 90 s and 100 s for desorption and adsorption, respectively. It is for the first time to apply side-chain-type sulfonated polymer electrolyte to humidity sensors and this new kind of sensitivity material showed a good application prospect.