Polyion Complex Fiber and Capsule Formed by Self-Assembly of Chitosan and Poly(α,L-glutamic acid) at Solution Interfaces

Abstract

Different characteristic surface structures such as spherical capsules, regularly spaced droplets and fibers are formed by electrostatic polysaccharide interaction between chitosan and poly(α,L-glutamic acid) via polyion complex (PIC) formation. Spherical droplet-like PIC capsules of varying diameters form in solutions. Some dyes absorb on the surface of the capsules, while other dyes and benzoic acid derivatives penetrate into the capsules. The PIC fiber can be prepared by reactive-spinning at the solution interface, followed by gravity and by removing water in ethanol. The tensile strength of the fiber is 11.2 kg . mm -2 (1.48 g . denier -1 ) and the knotting stength is 2.15 kg . mm -2 (0.30 g . d -1 ). By reaction with an organic cross-linking agent, ethylene glycol diglydyl ether (EGDE), the tensile strength of the fiber can be increased to 18.1 kg . mm -2 (3.14 g . d -1 ), and by reacting with hexamethylene diisocyanate (HMDI), the knotting strength of the fiber can be increased to 7.58 kg . mm-2 (0.89 g . d -1 ). The interaction energies (work of absorption, W ads ) of PLG and chitosan in aqueous solution xere estimated by a surface chemical aaprroach, and a relationship between the W ads values and the tensile strength of the PIC fibers and the Wads indicated that the higher W ads system gives the higher tensile strength. The PIC fiber can be dyed by four different dyeing procedure such as direct and vat dyeings. When the cross-linked PIC fibers was incubated in an aqueous solution in the presence of endocrine disruptor related compounds such as dibenzofuran and biphenyls, these compounds were accumalated onto and/or into the fibers.