Polyion complex fiber and capsule formed by self-assembly of chitosan and gellan at solution interfaces

Abstract

Different characteristic surface structures such as spheres and hemispheres, honeycomb, regularly spaced droplets and fibers are formed by electrostatic polysaccharide interaction between chitosan and gellan gum via polyion complex (PIC) formation. Spherical droplet-like PIC capsules of varying diameter form in solution. Some dyes adsorb on the surface of the capsules, while other dyes and benzoic acid penetrate into the capsules. The PIC fiber is spinnable by gravity and wet spinning in ethanol. This fiber possesses a counterion pairing structures and exhibits a nervation/veining pattern or a hollow yarn pattern. The tensile strength of the fiber is 18.4 kg/mm 2 (2.42 g/denier) and the knotting strength is 3.0 kg/mm 2 (0.40 g/d). By reaction with an organic cross-linking agent, e.g., hexamethylene diisocyanate, the tensile and knotting strengths of the fiber increased to 36.0 kg/mm 2 (3.99 g/d) and 9.2 kg/mm 2 (1.07 g/d), respectively. The PIC fiber can be dyed by different dyeing procedures such as direct and vat dyeing.