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A facile slow-gel method for bulk Al-doped carboxymethyl cellulose aerogels with excellent flame retardancy

Hu, Wenbin, Lu, Lingbin, Li, Zhanying, Shao, Lin
Carbohydrate polymers 2019 v.207 pp. 352-361
aerogels, aluminum, carboxymethylcellulose, freeze drying, metal ions, moieties, nitrogen, porous media
Bulk Al-doped carboxymethyl cellulose aerogels were obtained via a facile slow-gel method and freeze-drying technology. In this method, the cross-linker Al3+ was released slowly and completely with enough d-(+)-gluconic acid δ-lactone as a sustained-release agent. Depended on controlled releasing of Al3+, the reaction speed between Al3+ and carboxyl groups was controlled and Al3+ was well-distributed in the aerogels. The coordination type between Al3+ and carboxymethyl cellulose was the bidentate bridging coordination. By adjusting the amount of Al3+ and the degree of substitution of carboxymethyl cellulose, interconnected network and closely packed sheet-like structure presented, respectively. According to the nitrogen adsorption-desorption isotherms, the aerogels were a kind of mesoporous material with pore blocking or cavitation. In addition, the aerogels exhibited outstanding weight-bearing capacity and excellent flame retardancy. This work provided a valuable reference for doping metal ions into polysaccharide aerogels and expanding the application fields of aerogels.