Formation of Networked Structure Based on Polyion Complexation of Phytic Acid and Polyamines

Abstract

Phytic acid (PA) is a naturally occurring cyclic compound bearing six phosphoric acid monoester moieties. In this work, PA was combined with polyamines such as branched polyethyleneimine (BPEI) and chitosan expecting that the acidic moieties of PA and the amino groups of the polyamines would undergo neutralization to give polyion complexes composed of phosphate anions of PA molecules and ammonium cations of the polyamines. Upon mixing an aqueous solution of PA and that of BPEI, the corresponding polyion complex precipitated from the solution quickly. An aqueous solution that contains both PA and BPEI can be prepared by preventing their complexation by adding ammonia. When the solution thus prepared was casted on a Teflon plate and dried, a transparent and flexible film was obtained. On the other hand, the complexation of PA and chitosan was prevented by adding trifluoroacetic acid to enable the preparation of an aqueous solution containing both PA and chitosan. Removal of the volatiles from the solution on a silicone plate led to formation of a cast film of a PAchitosan polyion complex, which was transparent, flexible, and stable under a wide range of pH.