Preparation and properties of macromolecular complexes consisting of [2‐(diethylamino)ethyl]dextran hydrochloride and potassium metaphosphate

Abstract

AbstractIn aqueous solution [2‐(diethylamino)ethyl]dextran hydrochloride (EA) was reacted with potassium metaphosphate (MPK) to form a series of water‐insoluble macromolecular complexes (MC) at different hydrogen‐ion concentrations (EA–MPK system). EA was also reacted with MPK in the presence of CaCl2 (EA–MPK–CaCl2 system). The structure and properties of MC obtained were compared with each other; elemental analysis, IR spectroscopy, solubilities, thermogravimetric analysis, and scanning electron microscopy were used to characterize these complexes. The molecular structure and properties of each MC were dependent on the hydrogen‐ion concentration and whether the Ca2+ ion coexisted. It was suggested that MC prepared at acidic pH were composed of a relatively loose network including a small quantity of MPK, whereas those prepared at neutral and alkaline pH were composed of a relatively tight network including a large quantity of MPK. This seemed to be due to changes in the degree of dissociation and the conformation of EA and MPK with the hydrogen‐ion concentration. MC in the EA–MPK–CaCl2 system were supposed to have a rather tightly bound network structure due to the Ca2+ ion as compared with those in the EA–MPK system. © 1993 John Wiley & Sons, Inc.