2022 年 62 巻 12 号 p. 2536-2541
Desiccant humidity control systems have been garnering considerable attention in the attempt to achieve highly efficient utilization of low-temperature heat exhausted from various industries at temperatures less than 373 K. We have focused on thermosensitive polymers as new desiccants because a large amount of dehumidified water would be expected in the system because of their thermosensitivity. Our previous study focused on the water adsorption behavior of poly(N-isopropylacrylamide) (poly(NIPA)), which has a low critical solution temperature (LCST) of 306 K. In this study, poly(N-isopropylmethacrylamide) (poly(NIPMA)) and poly(2-(dimethylamino)ethyl methacrylate) (poly(DMAEMA)) cross-linked with N,N′-methylenebisacrylamide (MBAA) were investigated. These polymers are known to exhibit thermosensitivity in the temperature range of 313–319 K in water, which is a higher LCST than that of poly(NIPA). Poly(NIPMA) adsorbed water vapor linearly with increasing relative humidity. It was also observed that poly(NIPMA) prepared at MBAA concentrations of 200 mol/m3 exhibited a thermosensitivity in the temperature range of 303–313 K in water vapor adsorption. Meanwhile, poly(DMAEMA) adsorbed little water vapor up to a relative humidity (RH) of 40%; however, it exponentially adsorbed water at RH levels higher than 40%. From the estimation results of effective water adsorptivity, we found that poly(DMAEMA) is applicable in desiccant humidity control systems when the dehumidification process is performed at high RH.
