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 (PUSS) containing block copolymers (BCPs) of POSS-poly(methyl methacrylate)-polystyrene (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 more than 10(4) 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 (t(90%) of 11 s and 80 s in both the water adsorption and desorption processes), and superior repeatability for more than 30 days. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.