Cellulose/Chitosan Composite Multifilament Fibers with Two-Switch Shape Memory Performance

Because of the serious pollution caused by nondegradable plastic waste, environmentally benign materials from sustainable polymers have attracted tremendous research interest. Especially, functional fibers with good mechanical properties, shape memory behavior, and biodegradability have been required in the fields of smart textiles, sensors, and intelligent robots. Here, a new solvent, 4.5 wt % LiOH/7.5 wt % KOH/11.5 wt % urea aqueous solution, was developed to prepare stable cellulose/chitosan composite solution. Subsequently, cellulose/chitosan composite (CLS) fibers were spun successfully from the mixture solution on a lab-scale spinning machine. The CLS fibers exhibited good mechanical properties with tensile strength of 3.2 cN/dtex in the dry state and 2.9 cN/dtex in the wet state, as a result of the combination of good miscibility between two components and their nanofiber self-assembly driven by self-aggregation force through hydrogen bonding interactions. Interestingly, the CLS fibers showed a two-switch shape memory behaviors under water and acid stimulations. By changing the external stimulation, the strong self-aggregation force between cellulose and chitosan could be destroyed partly and then restructured to fix and recover, resulting in a designed shape. This work provided a new method for fabricating high strength and functional fibers for industry, which will promote the development of smart textiles.