Novel,tadpole-shaped,polyhedral oligomeric silsesquioxane containing sulfonated block copolymer for humidity sensing

Due to the "trade-off"effect between the high water adsorption and low stability under high Relative Humidity of polymer matrix,fabrication of resistive-type polymer-based humidity sensors with a wide impedance response and excellent stability in high relative humidity remains a great challenge.Aim at solving that,a novel polymeric humidity sensing matrix,specifically a tadpole-shaped,polyhedral oligomeric silsesquioxane(POSS) containing block copolymers(BCPs) of POSS-poly(methyl methacrylate)-poly styrene(POSS-PMMA-SPS) were proposed.This novel BCP was synthesized using atom transfer radical polymerization(ATRP) employing a two-step approach,and following post sulfonation,a series of sulfonated BCPs(POSS-PMMA-SPS) with different sulfonation degree was obtained.The subject humidity sensors were produced using different sulfonated BCPs employing a dip-coating technique,and three wide-impedance response humidity sensors were produced.Each of these sensors exhibited an excellent humidity-sensing response of mo re than 104 within the humidity range from 11% to 95% RH.In particular,the humidity sensor S-6 that had a proper degree of sulfonation presented a relatively fast response(tof 11 s and 80 s in both the water adsorption and desorption processes),and superior repeatability for more than 30 days.