Al3+ coordinated chitosan hydrogel with ultrahigh water absorbency and environmental response
Ze Zhang, Xiaodong Wang, Ting Liu, Lin Liu, Chenglong Yu, Yulin Tian, Xiaoxue Zhang, Jun Shen
Abstract
To fully utilize water, there is a great demand to develop eco-friendly materials with both ultra-high water absorbency and environmental response. In this study, the Al3+ coordinated chitosan (CIS-Al3+) hydrogels were prepared by formation of coordination bonds between Al3+ and the skeleton of CIS hydrogels. AlCl3 was used to provide coordination center, and the formaldehyde aqueous solution was chosen as crosslinker. The effect of Al3+ content and mass fraction of formaldehyde on gel formation, mechanical property and water storage capacity of CIS-Al3+ hydrogels was investigated deeply. The obtained CIS-Al3+ hydrogel can store more than 500% of its own weight of water without cracking, which demonstrates its super-absorbency. Besides, the CIS-Al3+ hydrogels can swell/shrink in response to the change of external stimuli such as temperature, pH and salinity. These outstanding properties, together with the low-cost raw materials, simple preparation method and biocompatible and biodegradable properties, enable CIS-Al3+ hydrogels to be applied as water storage materials in the agriculture field and pH-responsive materials in the future.