Repetitive use and effective recycling of the materials are vital to overcome the current environmental challenges. In case of polymeric materials, the high curing temperatures significantly limit their application. In this study, a series of polymers with thermal reversibility at room temperature were synthesized. The main chain of the polymer systems was composed of polyethylene glycol diglycidyl ether (PEGDGE) and polypropylene glycol diglycidyl ether (PPGDGE). The polymers were obtained by initial chain-extension of furfurylamine (FA) and subsequent Diels-Alder (DA) reaction with bismaleimide (BMI). Fourier transform infrared spectroscopy analysis revealed that the material exhibited fast curing rate and high conversion rate, with the conversion rate reaching 98 %. DSC and DMA characterization demonstrated that the reverse reaction occurred at about 100℃. The tensile analysis confirmed that the mechanical properties of the developed materials remain largely unchanged after recycling, as compared with the existing materials.
Low humidity monitoring has been attached to adequate attention in a wide range of industrial fields, such as medical device hermetic packaging, semiconductor manufacturing and transformer manufacturing. However, it remains challenging to detect slight moisture change in low-humidity environment for conventional ionic-type humidity sensors. Herein, Nickel (II) bromide (NiBr 2 ) is explored to be of a reversible moisture-induced discoloration behavior and highly sensitive to moisture in low humidity environment. NiBr 2 humidity sensor delivers a tremendous impedance change nearly to 5 orders of magnitude in the low relative humidity (RH) ranging from 7 % to 24 % and the response time is only about 2 s when RH increases from 11 % to 33 %. The excellent performance for low-humidity detection can be mainly attributed to the reversible bulk absorption behavior to water molecules that lead to a reversible material transition between NiBr 2 and NiBr 2 ⋅6H 2 O. Meanwhile, the sensitivity of the sensor toward the range of 7 %–24 % RH exhibits nearly 5 orders of magnitude enhancement than that in medium-high humidity range of 26 %–95 % RH, which indicates that the sensitivity of the sensor to water molecules caused by the bulk absorption behavior is better than that dominated by the surface adsorption behavior. The results demonstrate that the bulk absorption behavior-mediated reversible material transition provide efficient guidance to realize low-humidity detection.
危险品化学品经营许可证（带存储）