Dissolving cellulose in a NaOH/thiourea aqueous solution: a topochemical investigation.

Various kinds of cellulose/cellulose-aggregate films have been prepared on newly cleaved mica by the deposition of the suspensions of microcrystalline cellulose in water in the presence or in absence of NaOH/thiourea at different temperatures. The topochemistry of the cellulose surfaces have been directly observed by employing both SEM-EDX and AFM. These studies show that both NaOH and thiourea have a homogeneous distribution around the cellulose fibers during the dissolving process, and it is believed that their synergic interactions play a key role to dissolve the cellulose aggregates. It is also found that the dissolving process is continuous while the ice state formation promotes the dissolving process.