Preparation of bulk sodium carboxymethyl cellulose aerogels with tunable morphology.

Homogeneous and bulk carboxymethyl cellulose hydrogel and aerogel were prepared by a novel process, using Fe(3+) and d-(+)-gluconic acid-lactone as cross-linker and releasing agent, respectively. The results showed that the mass fraction of Fe(3+) has a great effect on CMC aerogels' structure, crystallization and morphology. By adjusting the mass fraction of Fe(3+), granular, three-dimensional network and rod-like morphology were obtained, responding to varying density and porosity. The aerogel had low density (low to 0.0568 g/cm(3)) and high porosity (up to 90.45%). Meantime. Combination patterns between carboxylate ion and iron ion were checked by FTIR. Furthermore, with the addition of Fe(3+), lattice mismatch of CMC emerged and led to decreasing crystalline degree and thermal stability. This work would play an important role in the handy and extensive application of CMC aerogels.